Merck & Co. (MRK) 10-Q3 May 242024 Q1 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2024	Apr. 30, 2024
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	1-6571
Entity Registrant Name	Merck & Co., Inc.
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	22-1918501
Entity Address, Address Line One	126 East Lincoln Avenue
Entity Address, City or Town	Rahway
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07065
City Area Code	(908)
Local Phone Number	740-4000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		2,532,806,307
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000310158
Current Fiscal Year End Date	--12-31
Common Stock ($0.50 par value)
Entity Information [Line Items]
Title of 12(b) Security	Common Stock ($0.50 par value)
Trading Symbol	MRK
Security Exchange Name	NYSE
0.500% Notes due 2024
Entity Information [Line Items]
Title of 12(b) Security	0.500% Notes due 2024
Trading Symbol	MRK 24
Security Exchange Name	NYSE
1.875% Notes due 2026
Entity Information [Line Items]
Title of 12(b) Security	1.875% Notes due 2026
Trading Symbol	MRK/26
Security Exchange Name	NYSE
2.500% Notes due 2034
Entity Information [Line Items]
Title of 12(b) Security	2.500% Notes due 2034
Trading Symbol	MRK/34
Security Exchange Name	NYSE
1.375% Notes due 2036
Entity Information [Line Items]
Title of 12(b) Security	1.375% Notes due 2036
Trading Symbol	MRK 36A
Security Exchange Name	NYSE

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENT OF INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Sales	$ 15,775	$ 14,487
Costs, Expenses and Other
Cost of sales	3,540	3,926
Selling, general and administrative	2,483	2,479
Research and development	3,992	4,276
Restructuring costs	123	67
Other (income) expense, net	(33)	89
Total Costs, Expenses and Other	10,105	10,837
Income Before Taxes	5,670	3,650
Taxes on Income	903	825
Net Income	4,767	2,825
Less: Net Income Attributable to Noncontrolling Interests	5	4
Net Income Attributable to Merck & Co., Inc.	$ 4,762	$ 2,821
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.88	$ 1.11
Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.87	$ 1.11

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 4,762	$ 2,821
Other Comprehensive Loss Net of Taxes:
Net unrealized gain (loss) on derivatives, net of reclassifications	130	(133)
Benefit plan net (loss) gain and prior service (cost) credit, net of amortization	(5)	(50)
Cumulative translation adjustment	(238)	68
Other comprehensive income (loss), net of taxes	(113)	(115)
Comprehensive Income Attributable to Merck & Co., Inc.	$ 4,649	$ 2,706

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEET - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current Assets
Cash and cash equivalents	$ 5,579	$ 6,841
Short-term investments	40	252
Accounts receivable (net of allowance for doubtful accounts of $80 in 2024 and $88 in 2023)	11,366	10,349
Inventories (excludes inventories of $3,413 in 2024 and $3,348 in 2023 classified in Other assets - see Note 6)	6,510	6,358
Other current assets	7,950	8,368
Total current assets	31,445	32,168
Investments	280	252
Property, Plant and Equipment, at cost, net of accumulated depreciation of $18,620 in 2024 and $18,266 in 2023	23,045	23,051
Goodwill	21,181	21,197
Other Intangibles, Net	17,572	18,011
Other Assets	12,326	11,996
Total Assets	105,849	106,675
Current Liabilities
Loans payable and current portion of long-term debt	3,077	1,372
Trade accounts payable	3,514	3,922
Accrued and other current liabilities	14,102	15,766
Income taxes payable	2,398	2,649
Dividends payable	2,008	1,985
Total current liabilities	25,099	25,694
Long-Term Debt	31,142	33,683
Deferred Income Taxes	922	871
Other Noncurrent Liabilities	8,262	8,792
Merck & Co., Inc. Stockholders’ Equity
Common stock, $0.50 par value Authorized - 6,500,000,000 shares Issued - 3,577,103,522 shares in 2024 and 2023	1,788	1,788
Other paid-in capital	44,598	44,509
Retained earnings	56,697	53,895
Accumulated other comprehensive loss	(5,274)	(5,161)
Stockholders' equity before deduction for treasury stock	97,809	95,031
Less treasury stock, at cost: 1,044,402,655 shares in 2024 and 1,045,470,249 shares in 2023	57,445	57,450
Total Merck & Co., Inc. stockholders’ equity	40,364	37,581
Noncontrolling Interests	60	54
Total equity	40,424	37,635
Liabilities and Equity	$ 105,849	$ 106,675

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 80	$ 88
Inventories classified in Other assets	3,413	3,348
Accumulated depreciation	$ 18,620	$ 18,266
Common stock, par value (in dollars per share)	$ 0.50	$ 0.50
Common stock, authorized (shares)	6,500,000,000	6,500,000,000
Common stock, issued (in shares)	3,577,103,522	3,577,103,522
Treasury stock (in shares)	1,044,402,655	1,045,470,249

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash Flows from Operating Activities
Net income	$ 4,767	$ 2,825
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization	473	543
Depreciation	511	448
Income from investments in equity securities, net	(143)	(450)
Charge for the acquisition of Harpoon Therapeutics, Inc.	656	0
Charge for the acquisition of Imago BioSciences, Inc.	0	1,192
Deferred income taxes	(51)	(277)
Share-based compensation	176	145
Other	83	(197)
Net changes in assets and liabilities	(3,382)	(2,890)
Net Cash Provided by Operating Activities	3,090	1,339
Cash Flows from Investing Activities
Capital expenditures	(861)	(1,007)
Purchases of securities and other investments	(15)	(562)
Proceeds from sales of securities and other investments	260	500
Acquisition of Harpoon Therapeutics, Inc., net of cash acquired	(746)	0
Acquisition of Imago BioSciences, Inc., net of cash acquired	0	(1,327)
Other	(14)	37
Net Cash Used in Investing Activities	(1,376)	(2,359)
Cash Flows from Financing Activities
Payments on debt	(751)	(1)
Dividends paid to stockholders	(1,950)	(1,853)
Purchases of treasury stock	(122)	(149)
Proceeds from exercise of stock options	87	30
Other	(78)	(81)
Net Cash Used in Financing Activities	(2,814)	(2,054)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(138)	87
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(1,238)	(2,987)
Cash, Cash Equivalents and Restricted Cash at Beginning of Year (includes restricted cash of $68 and $79 at January 1, 2024 and 2023, respectively, included in Other current assets)	6,909	12,773
Cash, Cash Equivalents and Restricted Cash at End of Period (includes restricted cash of $92 and $79 at March 31, 2024 and 2023, respectively, included in Other current assets)	$ 5,671	$ 9,786

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Statement of Cash Flows [Abstract]
Restricted cash	$ 92	$ 68	$ 79	$ 79

Basis of Presentation

Basis of Presentation	3 Months Ended
Basis of Presentation	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Merck & Co., Inc. (Merck or the Company) have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the United States (U.S.) for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited financial statements and notes thereto included in Merck’s Form 10-K filed on February 26, 2024. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year. In the Company’s opinion, all adjustments necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature. Certain reclassifications have been made to prior year amounts to conform to the current year presentation. Recently Issued Accounting Standards Not Yet Adopted In August 2023, the Financial Accounting Standards Board (FASB) issued amended guidance that requires a newly formed joint venture to recognize and initially measure its assets and liabilities at fair value upon formation. The amended guidance includes exceptions to fair value measurement that are consistent with the accounting for business combinations guidance. The amended guidance is effective prospectively for all joint ventures with a formation date on or after January 1, 2025, however existing joint ventures have the option to apply the guidance retrospectively. Early adoption is permitted for both interim and annual periods. The Company anticipates there will be no impact to its consolidated financial statements upon adoption. In November 2023, the FASB issued guidance intended to improve reportable segment disclosure requirements, primarily through expanded disclosures for significant segment expenses. The guidance is effective for annual periods beginning in 2024, and interim periods beginning in 2025. The guidance will result in incremental disclosures within the footnotes to the Company’s financial statements.

Acquisitions, Divestitures, Res

Acquisitions, Divestitures, Research Collaborations and Licensing Agreements	3 Months Ended
	Mar. 31, 2024
Business Combination and Asset Acquisition [Abstract]
Acquisitions, Divestitures, Research Collaborations and Licensing Agreements	Acquisitions, Divestitures, Research Collaborations and Licensing Agreements The Company continues to pursue acquisitions and the establishment of external alliances such as research collaborations and licensing agreements to complement its internal research capabilities. These arrangements often include upfront payments; expense reimbursements or payments to the third party; milestone, royalty or profit share arrangements contingent upon the occurrence of certain future events linked to the success of the asset in development; and can also include option and continuation payments. The Company also reviews its marketed products and pipeline to examine candidates which may provide more value through out-licensing and, as part of its portfolio assessment process, may also divest certain assets. Pro forma financial information for acquired businesses is not presented if the historical financial results of the acquired entity are not significant when compared with the Company’s financial results. 2024 Transactions In March 2024, Merck acquired Harpoon Therapeutics, Inc. (Harpoon), a clinical-stage immunotherapy company developing a novel class of T-cell engagers designed to harness the power of the body’s immune system to treat patients suffering from cancer and other diseases, for $765 million and also incurred $56 million of transaction costs. Harpoon’s lead candidate, MK-6070 (formerly HPN328), is a T-cell engager targeting delta-like ligand 3 (DLL3), an inhibitory canonical Notch ligand that is expressed at high levels in small-cell lung cancer (SCLC) and neuroendocrine tumors. MK-6070 is currently being evaluated as monotherapy in a Phase 1/2 clinical trial in certain patients with advanced cancers associated with expression of DLL3. The study is also evaluating MK-6070 in combination with atezolizumab in certain patients with SCLC. The transaction was accounted for as an asset acquisition since MK-6070 represented substantially all of the fair value of the gross assets acquired (excluding cash and deferred income taxes). Merck recorded net assets of $165 million, as well as a charge of $656 million to Research and development expenses in the first quarter of 2024 related to the transaction. There are no future contingent payments associated with the acquisition. In February 2024, Merck entered into a definitive agreement to acquire the aqua business of Elanco Animal Health Incorporated (Elanco) for $1.3 billion in cash. The Elanco aqua business to be acquired consists of an innovative portfolio of medicines and vaccines, nutritionals and supplements for aquatic species; two related aqua manufacturing facilities in Canada and Vietnam; as well as a research facility in Chile. Upon closing, the acquisition will broaden Animal Health’s aqua portfolio with products, such as Clynav, a new generation DNA-based vaccine that protects Atlantic salmon against pancreas disease, and Imvixa, an anti-parasitic sea lice treatment. This acquisition also brings a portfolio of water treatment products for warm water production, complementing Animal Health’s warm water vaccine portfolio. In addition to these products, the DNA-based vaccine technology that is a part of the business has the potential to accelerate the development of novel vaccines to address the unmet needs of the aqua industry. The acquisition is expected to be completed by mid-2024, subject to approvals from regulatory authorities and other customary closing conditions. The transaction will be accounted for as a business combination. 2023 Transactions In February 2023, Merck and Kelun-Biotech (a holding subsidiary of Sichuan Kelun Pharmaceutical Co., Ltd.) closed a license and collaboration agreement expanding their relationship in which Merck gained exclusive rights for the research, development, manufacture and commercialization of up to seven investigational preclinical antibody drug conjugates (ADCs) for the treatment of cancer. Kelun-Biotech retained the right to research, develop, manufacture and commercialize certain licensed and option ADCs for Chinese mainland, Hong Kong and Macau. Merck made an upfront payment of $175 million, which was recorded as a charge to Research and development expenses in the first quarter of 2023. In October 2023, Merck notified Kelun-Biotech it was terminating two of the seven candidates under the agreement. Subsequently, in April 2024, Merck notified Kelun-Biotech it was terminating an additional candidate under the agreement. Kelun-Biotech remains eligible to receive future contingent payments aggregating up to $600 million in development-related payments, $1.6 billion in regulatory milestones, and $3.1 billion in sales-based milestones if Kelun-Biotech does not retain Chinese mainland, Hong Kong and Macau rights for the option ADCs and all remaining candidates achieve regulatory approval. In addition, Kelun-Biotech is eligible to receive tiered royalties ranging from a mid-single-digit rate to a low-double-digit rate on future net sales for any commercialized ADC product. Also, in connection with the agreement, Merck invested $100 million in Kelun-Biotech shares in January 2023. In January 2023, Merck acquired Imago BioSciences, Inc. (Imago), a clinical stage biopharmaceutical company developing new medicines for the treatment of myeloproliferative neoplasms and other bone marrow diseases, for $1.35 billion (including payments to settle share-based equity awards) and also incurred approximately $60 million of transaction costs. Imago’s lead candidate, bomedemstat MK-3543 (formerly IMG-7289), is an investigational orally available lysine-specific demethylase 1 inhibitor currently being evaluated in multiple clinical trials for the treatment of essential thrombocythemia, myelofibrosis, and polycythemia vera, in addition to other indications. A Phase 3 clinical trial evaluating bomedemstat for the treatment of certain patients with essential thrombocythemia is underway. The transaction was accounted for as an acquisition of an asset since bomedemstat represented substantially all of the fair value of the gross assets acquired (excluding cash and deferred income taxes). Merck recorded net assets of $219 million, as well as a charge of $1.2 billion to Research and development expenses in the first quarter of 2023 related to the transaction. There are no future contingent payments associated with the acquisition. Spin-Off of Organon & Co. In connection with the 2021 spin-off of Organon & Co. (Organon), Merck and Organon entered into a series of interim operating agreements pursuant to which in various jurisdictions where Merck held licenses, permits and other rights in connection with marketing, import and/or distribution of Organon products prior to the separation, Merck continued to market, import and distribute such products on behalf of Organon until such time as the relevant licenses and permits transferred to Organon, with Organon receiving all of the economic benefits and burdens of such activities. As of March 31, 2024, only one jurisdiction remains under an interim operating agreement. Additionally, Merck and Organon entered into a number of manufacturing and supply agreements (MSAs) with terms ranging from four years to ten years. The amounts included in the condensed consolidated statement of income for the above MSAs include sales of $107 million and $94 million and related cost of sales of $110 million and $107 million for the first quarter of 2024 and 2023, respectively. The amounts due from Organon for all spin-off related agreements were $462 million and $632 million at March 31, 2024 and December 31, 2023, respectively, and are reflected in Other current assets . The amounts due to Organon under these agreements were $193 million and $598 million at March 31, 2024 and December 31, 2023, respectively, and are included in Accrued and other current liabilities .

Collaborative Arrangements

Collaborative Arrangements	3 Months Ended
Collaborative Arrangements	Mar. 31, 2024
Collaborative Arrangements [Abstract]
Collaborative Arrangements	Collaborative Arrangements Merck has entered into collaborative arrangements that provide the Company with varying rights to develop, produce and market products together with its collaborative partners. Both parties in these arrangements are active participants and exposed to significant risks and rewards dependent on the commercial success of the activities of the collaboration. Merck’s more significant collaborative arrangements are discussed below. AstraZeneca PLC In 2017, Merck and AstraZeneca PLC (AstraZeneca) entered into a global strategic oncology collaboration to co-develop and co-commercialize AstraZeneca’s Lynparza (olaparib) for multiple cancer types. Independently, Merck and AstraZeneca are developing and commercializing Lynparza in combinations with their respective PD-1 and PD-L1 medicines, Keytruda (pembrolizumab) and Imfinzi. The companies are also jointly developing and commercializing AstraZeneca’s Koselugo (selumetinib) for multiple indications. Under the terms of the agreement, AstraZeneca and Merck share the development and commercialization costs for Lynparza and Koselugo monotherapy and non-PD-L1/PD-1 combination therapy opportunities. Profits from Lynparza and Koselugo product sales generated through monotherapies or combination therapies are shared equally. AstraZeneca is the principal on Lynparza and Koselugo sales transactions. Merck records its share of Lynparza and Koselugo product sales, net of cost of sales and commercialization costs, as alliance revenue, and its share of development costs associated with the collaboration as part of Research and development expenses. Reimbursements received from AstraZeneca for research and development expenses are recognized as reductions to Research and development costs. As part of the agreement, Merck made an upfront payment to AstraZeneca and also made payments over a multi-year period for certain license options. In addition, the agreement provides for contingent payments from Merck to AstraZeneca related to the successful achievement of sales-based and regulatory milestones. In 2022, Merck determined it was probable that sales of Lynparza in the future would trigger a $600 million sales-based milestone payment from Merck to AstraZeneca. Accordingly, Merck recorded a $600 million liability (which remained accrued at March 31, 2024) and a corresponding increase to the intangible asset related to Lynparza. Potential future sales-based milestone payments of $2.1 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. Lynparza received regulatory approvals triggering capitalized milestone payments from Merck to AstraZeneca of $245 million and $105 million in the first quarter of 2024 and 2023, respectively (each of which had been previously accrued for). Potential future regulatory milestone payments of $650 million remain under the agreement. The intangible asset balance related to Lynparza (which includes capitalized sales-based and regulatory milestone payments) was $1.4 billion at March 31, 2024 and is included in Other Intangibles, Net . The amount is being amortized over its estimated useful life through 2028 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Alliance revenue - Lynparza $ 292 $ 275 Alliance revenue - Koselugo 38 23 Total alliance revenue $ 330 $ 298 Cost of sales (1) 82 70 Selling, general and administrative 39 47 Research and development 20 21 ($ in millions) March 31, 2024 December 31, 2023 Receivables from AstraZeneca included in Other current assets $ 334 $ 341 Payables to AstraZeneca included in Accrued and other current liabilities (2) 617 256 Payables to AstraZeneca included in Other Noncurrent Liabilities (2) — 600 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone payments. Eisai Co., Ltd. In 2018, Merck and Eisai Co., Ltd. (Eisai) announced a strategic collaboration for the worldwide co-development and co-commercialization of Lenvima (lenvatinib), an orally available tyrosine kinase inhibitor discovered by Eisai. Under the agreement, Merck and Eisai are developing and commercializing Lenvima jointly, both as monotherapy and in combination with Keytruda . Eisai records Lenvima product sales globally (Eisai is the principal on Lenvima sales transactions) and Merck and Eisai share applicable profits equally. Merck records its share of Lenvima product sales, net of cost of sales and commercialization costs, as alliance revenue. Expenses incurred during co-development are shared by the two companies in accordance with the collaboration agreement and reflected in Research and development expenses. Certain expenses incurred solely by Merck or Eisai are not shareable under the collaboration agreement, including costs incurred in excess of agreed upon caps and costs related to certain combination studies of Keytruda and Lenvima. Under the agreement, Merck made an upfront payment to Eisai and also made payments over a multi-year period for certain option rights. In addition, the agreement provides for contingent payments from Merck to Eisai related to the successful achievement of sales-based and regulatory milestones. In the first quarter of 2023, Merck determined it was probable that sales of Lenvima in the future would trigger a $125 million sales-based milestone payment from Merck to Eisai. Similarly, in the third quarter of 2023 an additional $125 million sales-based milestone payment to Eisai was deemed by the Company to be probable of payment. Accordingly, Merck recorded $250 million of liabilities for these payments (of which $125 million was subsequently paid in the second quarter of 2023 and $125 million remained accrued at March 31, 2024) and corresponding increases to the intangible asset related to Lenvima. Merck also recognized $72 million and $81 million of cumulative amortization catch-up expense related to the recognition of these milestones in the first and third quarters of 2023, respectively. Potential future sales-based milestone payments of $2.3 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. There are no regulatory milestone payments remaining under the agreement. The intangible asset balance related to Lenvima (which includes capitalized sales-based and regulatory milestone payments) was $623 million at March 31, 2024 and is included in Other Intangibles, Net . The amount is being amortized over its estimated useful life through 2026 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Alliance revenue - Lenvima $ 255 $ 232 Cost of sales (1) 60 126 Selling, general and administrative 39 51 Research and development 8 39 ($ in millions) March 31, 2024 December 31, 2023 Receivables from Eisai included in Other current assets $ 255 $ 226 Payables to Eisai included in Accrued and other current liabilities (2) 125 125 (1) Represents amortization of capitalized milestone payments. Amount in the first quarter of 2023 includes $72 million of cumulative amortization catch-up expense as noted above. (2) Represents an accrued milestone payment. Bayer AG In 2014, the Company entered into a worldwide clinical development collaboration with Bayer AG (Bayer) to market and develop soluble guanylate cyclase (sGC) modulators including Bayer’s Adempas (riociguat) and Verquvo (vericiguat). The two companies have implemented a joint development and commercialization strategy. Under the agreement, Bayer commercializes Adempas in the Americas, while Merck commercializes in the rest of the world. For Verquvo, Merck commercializes in the U.S. and Bayer commercializes in the rest of the world. Both companies share in development costs and profits on sales. Merck records sales of Adempas and Verquvo in its marketing territories, as well as alliance revenue. Alliance revenue represents Merck’s share of profits from sales of Adempas and Verquvo in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs. Cost of sales includes Bayer’s share of profits from sales in Merck’s marketing territories. In addition, the agreement provided for contingent payments from Merck to Bayer related to the successful achievement of sales-based milestones. There are no sales-based milestone payments remaining under this collaboration. The intangible asset balances related to Adempas (which includes the acquired intangible asset balance, as well as capitalized sales-based milestone payments attributed to Adempas) and Verquvo (which reflects the portion of the final sales-based milestone payment that was attributed to Verquvo) were $483 million and $49 million, respectively, at March 31, 2024 and are included in Other Intangibles, Net . The assets are being amortized over their estimated useful lives (through 2027 for Adempas and through 2031 for Verquvo) as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Alliance revenue - Adempas/Verquvo $ 98 $ 99 Net sales of Adempas recorded by Merck 70 59 Net sales of Verquvo recorded by Merck 5 7 Total sales $ 173 $ 165 Cost of sales (1) 62 57 Selling, general and administrative 33 33 Research and development 28 25 ($ in millions) March 31, 2024 December 31, 2023 Receivables from Bayer included in Other current assets $ 155 $ 156 Payables to Bayer included in Accrued and other current liabilities 74 80 (1) Includes amortization of intangible assets, cost of products sold by Merck, as well as Bayer’s share of profits from sales in Merck’s marketing territories. Ridgeback Biotherapeutics LP In 2020, Merck and Ridgeback Biotherapeutics LP (Ridgeback), a closely held biotechnology company, entered into a collaboration agreement to develop Lagevrio (molnupiravir), an investigational orally available antiviral candidate for the treatment of patients with COVID-19. Merck gained exclusive worldwide rights to develop and commercialize Lagevrio and related molecules. Following initial authorizations in certain markets in the fourth quarter of 2021, Lagevrio has since received multiple additional authorizations. Under the terms of the agreement, Ridgeback received an upfront payment and is eligible to receive future contingent payments dependent upon the achievement of certain developmental and regulatory approval milestones. The agreement also provides for Merck to reimburse Ridgeback for a portion of certain third-party contingent milestone payments and royalties on net sales, which is part of the profit-sharing calculation. Merck is the principal on sales transactions, recognizing sales and related costs, with profit-sharing amounts recorded within Cost of sales . Profits from the collaboration are split equally between the partners. Reimbursements from Ridgeback for its share of research and development costs (deducted from Ridgeback’s share of profits) are reflected as decreases to Research and development expenses. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Net sales of Lagevrio recorded by Merck $ 350 $ 392 Cost of sales (1) 191 221 Selling, general and administrative 16 27 Research and development (5) 16 ($ in millions) March 31, 2024 December 31, 2023 Payables to Ridgeback included in Accrued and other current liabilities (2) $ 160 $ 113 (1) Includes cost of products sold by Merck, Ridgeback’s share of profits, royalty expense, amortization of capitalized milestone payments and inventory reserves. (2) Includes accrued royalties. Daiichi Sankyo In October 2023, Merck and Daiichi Sankyo entered into a global development and commercialization agreement for three of Daiichi Sankyo’s DXd ADC candidates: patritumab deruxtecan (HER3-DXd) (MK-1022), ifinatamab deruxtecan (I-DXd) (MK-2400) and raludotatug deruxtecan (R-DXd) (MK-5909). All three potentially first-in-class DXd ADCs are in various stages of clinical development for the treatment of multiple solid tumors both as monotherapy and/or in combination with other treatments. The companies will jointly develop and potentially commercialize these ADC candidates worldwide, except in Japan where Daiichi Sankyo will maintain exclusive rights. Daiichi Sankyo will be solely responsible for manufacturing and supply. Under the terms of the agreement, Merck made payments to Daiichi Sankyo totaling $4.0 billion in 2023. These payments included $1.0 billion ($500 million each for patritumab deruxtecan and ifinatamab deruxtecan) which may be refundable on a pro-rated basis in the event of early termination of development with respect to either program. In addition, the agreement provides for a continuation payment of $750 million related to patritumab deruxtecan due from Merck in October 2024 and a continuation payment of $750 million related to raludotatug deruxtecan due from Merck in October 2025. If Merck does not make the continuation payments on the dates noted for either patritumab deruxtecan and/or raludotatug deruxtecan, the rights for the applicable program will revert to Daiichi Sankyo and the non-refundable upfront payments already paid will be retained by Daiichi Sankyo. The agreement also provides for contingent payments from Merck to Daiichi Sankyo of up to an additional $5.5 billion for each DXd ADC upon the successful achievement of certain sales-based milestones. In conjunction with this transaction, Merck recorded an aggregate pretax charge of $5.5 billion to Research and development expenses in the fourth quarter of 2023 for the $4.0 billion of upfront payments and the $1.5 billion of continuation payments. Merck and Daiichi Sankyo will equally share research and development costs, except for raludotatug deruxtecan, where Merck will be responsible for 75% of the first $2.0 billion of research and development expenses. Merck includes its share of development costs associated with the collaboration as part of Research and development expenses. Following regulatory approval, Daiichi Sankyo will generally record sales worldwide (Daiichi Sankyo will be the principal on sales transactions) and the companies will equally share expenses as well as profits worldwide except for Japan where Daiichi Sankyo retains exclusive rights and Merck will receive a 5% sales-based royalty. Merck will record its share of product sales, net of cost of sales and commercialization costs, as alliance revenue. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Selling, general and administrative $ 3 $ — Research and development 69 — ($ in millions) March 31, 2024 December 31, 2023 Payables to Daiichi Sankyo included in Accrued and other current liabilities $ 817 $ 800 Payables to Daiichi Sankyo included in Other Noncurrent Liabilities 750 750 Moderna, Inc. In 2022, Merck exercised its option to jointly develop and commercialize V940 (mRNA-4157), an investigational individualized neoantigen therapy, pursuant to the terms of an existing collaboration and license agreement with Moderna, Inc. (Moderna). V940 (mRNA-4157) is currently being evaluated in combination with Keytruda in multiple Phase 3 clinical trials. Merck and Moderna will share costs and any profits equally under this worldwide collaboration. Merck records its share of development costs associated with the collaboration as part of Research and development expenses. Any reimbursements received from Moderna for research and development expenses are recognized as reductions to Research and development costs. Merck has also capitalized certain of the shared costs, which aggregated $110 million at March 31, 2024 and will be amortized over the assets’ estimated useful lives. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Selling, general and administrative $ 2 $ 1 Research and development 69 26 ($ in millions) March 31, 2024 December 31, 2023 Payables to Moderna included in Accrued and other current liabilities $ 72 $ 63 Bristol-Myers Squibb Company Reblozyl (luspatercept-aamt) is a first-in-class erythroid maturation recombinant fusion protein that is being commercialized through a global collaboration with Bristol-Myers Squibb Company (BMS). Reblozyl is approved in the U.S., Europe and certain other markets for the treatment of anemia in certain rare blood disorders and is also being evaluated for additional indications for hematology therapies. BMS is the principal on sales transactions for Reblozyl; however, Merck co-promotes Reblozyl (and will co-promote all future products approved under this collaboration) in North America, which is reimbursed by BMS. Merck receives tiered royalties ranging from 20% to 24% based on sales levels. This royalty will be reduced by 50% upon the earlier of patent expiry or generic entry on an indication-by-indication basis in each market. Additionally, Merck is eligible to receive future contingent sales-based milestone payments of up to $80 million. Alliance revenue related to this collaboration, consisting of royalties (recorded within Sales ) was $71 million and $43 million in the first quarter of 2024 and 2023, respectively.

Restructuring

Restructuring	3 Months Ended
Restructuring	Mar. 31, 2024
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring In January 2024, the Company approved a new restructuring program (2024 Restructuring Program) intended to continue the optimization of the Company’s Human Health global manufacturing network as the future pipeline shifts to new modalities and also optimize the Animal Health global manufacturing network to improve supply reliability and increase efficiency. The actions contemplated under the 2024 Restructuring Program are expected to be substantially completed by the end of 2031, with the cumulative pretax costs to be incurred by the Company to implement the program estimated to be approximately $4.0 billion. Approximately 60% of the cumulative pretax costs will be non-cash, relating primarily to the accelerated depreciation of facilities to be closed or divested. The remainder of the costs will result in cash outlays, relating primarily to facility shut-down costs. The Company recorded total pretax costs of $246 million in the first quarter of 2024 related to the 2024 Restructuring Program, bringing total cumulative pretax costs incurred through March 31, 2024 to $436 million. In 2019, Merck approved a global restructuring program (2019 Restructuring Program) as part of a worldwide initiative focused on optimizing the Company’s manufacturing and supply network, as well as reducing its global real estate footprint. The Company recorded total pretax costs of $97 million in the first quarter of 2023 related to the 2019 Restructuring Program. The actions under the 2019 Restructuring Program were substantially complete at the end of 2023 and, as of January 1, 2024, any remaining activities are now being accounted for as part of the 2024 Restructuring Program. For segment reporting, restructuring charges are unallocated expenses. The following tables summarize the charges related to the restructuring programs by type of cost: Three Months Ended March 31, 2024 ($ in millions) Accelerated Depreciation Separation Costs Other Exit Costs Total 2024 Restructuring Program Cost of sales $ 65 $ — $ 51 $ 116 Selling, general and administrative — — 5 5 Research and development — — 2 2 Restructuring costs — 92 31 123 $ 65 $ 92 $ 89 $ 246 Three Months Ended March 31, 2023 ($ in millions) Accelerated Depreciation Separation Costs Other Exit Costs Total 2019 Restructuring Program Cost of sales $ 21 $ — $ 8 $ 29 Selling, general and administrative — — 1 1 Restructuring costs — 41 26 67 $ 21 $ 41 $ 35 $ 97 Accelerated depreciation costs primarily relate to manufacturing, research and administrative facilities and equipment to be sold or closed as part of the programs. Accelerated depreciation costs represent the difference between the depreciation expense to be recognized over the revised useful life of the asset, based upon the anticipated date the site will be closed or divested or the equipment disposed of, and depreciation expense as determined utilizing the useful life prior to the restructuring actions. All the sites will continue to operate up through the respective closure dates and, since future undiscounted cash flows are sufficient to recover the respective book values, Merck is recording accelerated depreciation over the revised useful life of the site assets. Anticipated site closure dates, particularly related to manufacturing locations, have been and may continue to be adjusted to reflect changes resulting from regulatory or other factors. Separation costs are associated with actual headcount reductions, as well as involuntary headcount reductions which were probable and could be reasonably estimated. Other exit costs in 2024 and 2023 include asset abandonment, facility shut-down and other related costs, as well as pretax gains and losses resulting from the sales of facilities and related assets. Additionally, other activity includes certain employee-related costs associated with pension and other postretirement benefit plans (see Note 9) and share-based compensation. The following table summarizes the charges and spending relating to restructuring program activities for the three months ended March 31, 2024: ($ in millions) Accelerated Depreciation Separation Costs Other Exit Costs Total Restructuring reserves January 1, 2024 $ — $ 681 $ 31 $ 712 Expenses 65 92 89 246 (Payments) receipts, net — (67) (32) (99) Non-cash activity (65) — (58) (123) Restructuring reserves March 31, 2024 $ — $ 706 $ 30 $ 736

Financial Instruments

Financial Instruments	3 Months Ended
Financial Instruments	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments Derivative Instruments and Hedging Activities The Company manages the impact of foreign exchange rate movements and interest rate movements on its earnings, cash flows and fair values of assets and liabilities through operational means and through the use of various financial instruments, including derivative instruments. A significant portion of the Company’s revenues and earnings in foreign affiliates is exposed to changes in foreign exchange rates. The objectives of and accounting related to the Company’s foreign currency risk management program, as well as its interest rate risk management activities are discussed below. Foreign Currency Risk Management The Company has established revenue hedging, balance sheet risk management and net investment hedging programs to protect against volatility of future foreign currency cash flows and changes in fair value caused by changes in foreign exchange rates. The objective of the revenue hedging program is to reduce the variability caused by changes in foreign exchange rates that would affect the U.S. dollar value of future cash flows derived from foreign currency denominated sales, primarily the euro, Japanese yen and Chinese renminbi. To achieve this objective, the Company will hedge a portion of its forecasted foreign currency denominated third-party and intercompany distributor entity sales (forecasted sales) that are expected to occur over its planning cycle, typically no more than two years into the future. The Company will layer in hedges over time, increasing the portion of forecasted sales hedged as it gets closer to the expected date of the forecasted sales. The portion of forecasted sales hedged is based on assessments of cost-benefit profiles that consider natural offsetting exposures, revenue and foreign exchange rate volatilities and correlations, and the cost of hedging instruments. The Company manages its anticipated transaction exposure principally with purchased local currency put options, forward contracts, and purchased collar options. The fair values of these derivative contracts are recorded as either assets (gain positions) or liabilities (loss positions) in the Condensed Consolidated Balance Sheet. Changes in the fair value of derivative contracts are recorded each period in either current earnings or Other comprehensive income ( OCI ), depending on whether the derivative is designated as part of a hedge transaction and, if so, the type of hedge transaction. For derivatives that are designated as cash flow hedges, the unrealized gains or losses on these contracts are recorded in Accumulated Other Comprehensive Loss ( AOCL) and reclassified into Sales when the hedged anticipated revenue is recognized. For those derivatives which are not designated as cash flow hedges, but serve as economic hedges of forecasted sales, unrealized gains or losses are recorded in Sales each period. The cash flows from both designated and non-designated contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. The Company does not enter into derivatives for trading or speculative purposes. The Company manages operating activities and net asset positions at each local subsidiary in order to mitigate the effects of foreign exchange on monetary assets and liabilities. Monetary assets and liabilities denominated in a currency other than the functional currency of a given subsidiary are remeasured at spot rates in effect on the balance sheet date with the effects of changes in spot rates reported in Other (income) expense, net . The Company also uses a balance sheet risk management program to mitigate the exposure of such assets and liabilities from the effects of volatility in foreign exchange. Merck principally utilizes forward exchange contracts to offset the effects of foreign exchange on exposures when it is deemed economical to do so based on a cost-benefit analysis that considers the magnitude of the exposure, the volatility of the foreign exchange rate and the cost of the hedging instrument (primarily the euro, Swiss franc, Japanese yen, and Chinese renminbi). The forward contracts are not designated as hedges and are marked to market through Other (income) expense, net . Accordingly, fair value changes in the forward contracts help mitigate the changes in the value of the remeasured assets and liabilities attributable to changes in foreign currency exchange rates, except to the extent of the spot-forward differences. These differences are not significant due to the short-term nature of the contracts, which typically have average maturities at inception of less than six months. The cash flows from these contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. The Company also uses forward exchange contracts to hedge a portion of its net investment in foreign operations against movements in foreign exchange rates. The forward contracts are designated as hedges of the net investment in a foreign operation. The unrealized gains or losses on these contracts are recorded in foreign currency translation adjustment within OCI and remain in AOCL until either the sale or complete or substantially complete liquidation of the subsidiary. The Company excludes certain portions of the change in fair value of its derivative instruments from the assessment of hedge effectiveness (excluded components). Changes in fair value of the excluded components are recognized in OCI . The Company recognizes in earnings the initial value of the excluded components on a straight-line basis over the life of the derivative instrument, rather than using the mark-to-market approach. The cash flows from these contracts are reported as investing activities in the Condensed Consolidated Statement of Cash Flows. Foreign exchange risk is also managed through the use of foreign currency debt. The Company’s senior unsecured euro-denominated notes have been designated as, and are effective as, economic hedges of the net investment in a foreign operation. Accordingly, foreign currency transaction gains or losses due to spot rate fluctuations on the euro-denominated debt instruments are included in foreign currency translation adjustment within OCI . The effects of the Company’s net investment hedges on OCI and the Condensed Consolidated Statement of Income are shown below: Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) Amount of Pretax Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing Three Months Ended March 31, Three Months Ended March 31, ($ in millions) 2024 2023 2024 2023 Net Investment Hedging Relationships Foreign exchange contracts $ (2) $ 1 $ — $ 1 Euro-denominated notes (62) 52 — — (1) No amounts were reclassified from AOCL into income related to the sale of a subsidiary. Interest Rate Risk Management The Company may use interest rate swap contracts on certain investing and borrowing transactions to manage its net exposure to interest rate changes and to reduce its overall cost of borrowing. The Company does not use leveraged swaps and, in general, does not leverage any of its investment activities that would put principal at risk. At March 31, 2024, the Company was a party to four pay-floating, receive-fixed interest rate swap contracts designated as fair value hedges of a portion of fixed-rate notes as detailed in the table below. March 31, 2024 ($ in millions) Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 4.50% notes due 2033 $ 1,500 4 $ 1,000 The interest rate swap contracts are designated hedges of the fair value changes in the notes attributable to changes in the benchmark Secured Overnight Financing Rate (SOFR) swap rate. The fair value changes in the notes attributable to changes in the SOFR swap rate are recorded in interest expense along with the offsetting fair value changes in the swap contracts. The cash flows from these contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. In April 2024, the Company entered into two additional interest rate swaps with notional amounts of $250 million each also related to its 4.50% notes due 2033. The table below presents the location of amounts recorded in the Condensed Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase Included in the Carrying Amount ($ in millions) March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Balance Sheet Caption Long-Term Debt $ 1,026 $ 1,056 $ 26 $ 56 Presented in the table below is the fair value of derivatives on a gross basis segregated between those derivatives that are designated as hedging instruments and those that are not designated as hedging instruments: March 31, 2024 December 31, 2023 Fair Value of Derivative U.S. Dollar Fair Value of Derivative U.S. Dollar ($ in millions) Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Balance Sheet Caption Interest rate swap contracts Other Assets $ 27 $ — $ 1,000 $ 57 $ — $ 1,000 Foreign exchange contracts Other current assets 175 — 9,082 106 — 6,138 Foreign exchange contracts Other Assets 32 — 2,062 26 — 1,929 Foreign exchange contracts Accrued and other current liabilities — 10 1,076 — 76 3,680 Foreign exchange contracts Other Noncurrent Liabilities — 1 204 — 1 7 234 11 13,424 189 77 12,754 Derivatives Not Designated as Hedging Instruments Balance Sheet Caption Foreign exchange contracts Other current assets 121 — 9,428 153 — 9,693 Foreign exchange contracts Other Assets 2 — 43 — — — Foreign exchange contracts Accrued and other current liabilities — 154 9,282 — 162 8,104 Foreign exchange contracts Other Noncurrent Liabilities — 2 43 — — — 123 156 18,796 153 162 17,797 $ 357 $ 167 $ 32,220 $ 342 $ 239 $ 30,551 As noted above, the Company records its derivatives on a gross basis in the Condensed Consolidated Balance Sheet. The Company has master netting agreements with several of its financial institution counterparties (see Concentrations of Credit Risk below). The following table provides information on the Company’s derivative positions subject to these master netting arrangements as if they were presented on a net basis, allowing for the right of offset by counterparty and cash collateral exchanged per the master agreements and related credit support annexes: March 31, 2024 December 31, 2023 ($ in millions) Asset Liability Asset Liability Gross amounts recognized in the condensed consolidated balance sheet $ 357 $ 167 $ 342 $ 239 Gross amounts subject to offset in master netting arrangements not offset in the condensed consolidated balance sheet (111) (111) (215) (215) Cash collateral received (58) — (3) — Net amounts $ 188 $ 56 $ 124 $ 24 The table below provides information regarding the location and amount of pretax gains and losses of derivatives designated in fair value or cash flow hedging relationships: Three Months Ended March 31, ($ in millions) 2024 2023 2024 2023 2024 2023 Financial Statement Caption in which Effects of Fair Value or Cash Flow Hedges are Recorded Sales Other (income) expense, net (1) Other comprehensive income (loss) $ 15,775 $ 14,487 $ (33) $ 89 $ (113) $ (115) (Gain) loss on fair value hedging relationships: Interest rate swap contracts Hedged items — — (30) — — — Derivatives designated as hedging instruments — — 30 — — — Impact of cash flow hedging relationships: Foreign exchange contracts Amount of gain (loss) recognized in OCI on derivatives — — — — 209 (66) Increase in Sales as a result of AOCL reclassifications 44 101 — — (44) (101) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — — (1) — — Amount of loss recognized in OCI on derivatives — — — — — (1) (1) Interest expense is a component of Other (income) expense, net. The table below provides information regarding the income statement effects of derivatives not designated as hedging instruments: Amount of Derivative Pretax (Gain) Loss Recognized in Income Three Months Ended March 31, ($ in millions) 2024 2023 Derivatives Not Designated as Hedging Instruments Income Statement Caption Foreign exchange contracts (1) Other (income) expense, net $ 65 $ 13 Foreign exchange contracts (2) Sales (10) 2 (1) These derivative contracts primarily mitigate changes in the value of remeasured foreign currency denominated monetary assets and liabilities attributable to changes in foreign currency exchange rates. (2) These derivative contracts serve as economic hedges of forecasted transactions . At March 31, 2024, the Company estimates $113 million of pretax net unrealized gains on derivatives maturing within the next 12 months that hedge foreign currency denominated sales over that same period will be reclassified from AOCL to Sales . The amount ultimately reclassified to Sales may differ as foreign exchange rates change. Realized gains and losses are ultimately determined by actual foreign exchange rates at maturity. Investments in Debt and Equity Securities Information on investments in debt and equity securities is as follows: March 31, 2024 December 31, 2023 Amortized Gross Unrealized Fair Amortized Gross Unrealized Fair ($ in millions) Gains Losses Gains Losses Commercial paper $ 40 $ — $ — $ 40 $ 252 $ — $ — $ 252 U.S. government and agency securities 77 — — 77 72 — — 72 Corporate notes and bonds — — — — 13 — — 13 Total debt securities $ 117 $ — $ — $ 117 $ 337 $ — $ — $ 337 Publicly traded equity securities (1) 908 764 Total debt and publicly traded equity securities $ 1,025 $ 1,101 (1) Unrealized net gains of $143 million were recorded in Other (income) expense, net in the first quarter of 2024 on equity securities still held at March 31, 2024. Unrealized net gains of $338 million were recorded in Other (income) expense, net in the first quarter of 2023 on equity securities still held at March 31, 2023. At March 31, 2024 and March 31, 2023, the Company also had $851 million and $942 million, respectively, of equity investments without readily determinable fair values included in Other Assets . The Company records unrealized gains on these equity investments based on favorable observable price changes from transactions involving similar investments of the same investee and records unrealized losses based on unfavorable observable price changes, which are included in Other (income) expense, net . During the first quarter of 2024 , the Company recorded unrealized gains of $4 million and unrealized losses of $5 million related to certain of these equity investments still held at March 31, 2024. During the first quarter of 2023 , the Company recorded unrealized gains of $1 million and unrealized losses of $21 million related to certain of these equity investments still held at March 31, 2023. Cumulative unrealized gains and cumulative unrealized losses based on observable price changes for investments in equity investments without readily determinable fair values still held at March 31, 2024 were $297 million and $69 million, respectively. At March 31, 2024 and March 31, 2023, the Company also had $396 million and $725 million, respectively, recorded in Other Assets for equity securities held through ownership interests in investment funds. Losses (gains) recorded in Other (income) expense, net relating to these investment funds were $2 million and $(132) million for the first quarter of 2024 and 2023, respectively. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company uses a fair value hierarchy which maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. There are three levels of inputs used to measure fair value with Level 1 having the highest priority and Level 3 having the lowest: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 - Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity. Level 3 assets or liabilities are those whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques with significant unobservable inputs, as well as assets or liabilities for which the determination of fair value requires significant judgment or estimation. If the inputs used to measure the financial assets and liabilities fall within more than one level described above, the categorization is based on the lowest level input that is significant to the fair value measurement of the instrument. Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis Financial assets and liabilities measured at fair value on a recurring basis are summarized below: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ($ in millions) March 31, 2024 December 31, 2023 Assets Investments Commercial paper $ — $ 40 $ — $ 40 $ — $ 252 $ — $ 252 Publicly traded equity securities 280 — — 280 252 — — 252 280 40 — 320 252 252 — 504 Other assets (1) U.S. government and agency securities 77 — — 77 72 — — 72 Corporate notes and bonds — — — — 13 — — 13 Publicly traded equity securities (2) 628 — — 628 512 — — 512 705 — — 705 597 — — 597 Derivative assets (3) Forward exchange contracts — 204 — 204 — 202 — 202 Purchased currency options — 126 — 126 — 83 — 83 Interest rate swaps — 27 — 27 — 57 — 57 — 357 — 357 — 342 — 342 Total assets $ 985 $ 397 $ — $ 1,382 $ 849 $ 594 $ — $ 1,443 Liabilities Other liabilities Contingent consideration $ — $ — $ 226 $ 226 $ — $ — $ 354 $ 354 Derivative liabilities (3) Forward exchange contracts — 149 — 149 — 239 — 239 Written currency options — 18 — 18 — — — — — 167 — 167 — 239 — 239 Total liabilities $ — $ 167 $ 226 $ 393 $ — $ 239 $ 354 $ 593 (1) Investments included in other assets are restricted as to use, including for the payment of benefits under employee benefit plans. (2) Balance at March 31, 2024 includes securities with a fair value of $266 million, which are subject to a contractual sale restriction that expires in July 2024. (3) The fair value determination of derivatives includes the impact of the credit risk of counterparties to the derivatives and the Company’s own credit risk, the effects of which were not significant. As of March 31, 2024 and December 31, 2023, Cash and cash equivalents included $4.6 billion and $6.0 billion of cash equivalents, respectively (which would be considered Level 2 in the fair value hierarchy). Contingent Consideration Summarized information about the changes in the fair value of liabilities for contingent consideration associated with business combinations is as follows: ($ in millions) 2024 2023 Fair value January 1 $ 354 $ 456 Changes in estimated fair value (1) (2) 14 Payments (126) (117) Fair value March 31 (2) $ 226 $ 353 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at March 31, 2024, includes $133 million of current liabilities, all of which relate to the termination of the Sanofi Pasteur MSD joint venture in 2016. As part of the termination, Merck recorded a liability for contingent future royalty payments of 11.5% on net sales of all Merck products that were previously sold by the joint venture through December 31, 2024. The fair value of this liability is determined utilizing the estimated amount and timing of projected cash flows using a risk-adjusted discount rate to present value the cash flows. The payments of contingent consideration in both periods relate to the Sanofi Pasteur MSD liabilities described above. Other Fair Value Measurements Some of the Company’s financial instruments, such as cash and cash equivalents, receivables and payables, are reflected in the balance sheet at carrying value, which approximates fair value due to their short-term nature. The estimated fair value of loans payable and long-term debt (including current portion) at March 31, 2024, was $30.4 billion compared with a carrying value of $34.2 billion and at December 31, 2023, was $32.0 billion compared with a carrying value of $35.1 billion. Fair value was estimated using recent observable market prices and would be considered Level 2 in the fair value hierarchy. Concentrations of Credit Risk On an ongoing basis, the Company monitors concentrations of credit risk associated with corporate and government issuers of securities and financial institutions with which it conducts business. Credit exposure limits are established to limit a concentration with any single issuer or institution. Cash and investments are placed in instruments that meet high credit quality standards as specified in the Company’s investment policy guidelines. The majority of the Company’s accounts receivable arise from product sales in the U.S., Europe and China and are primarily due from drug wholesalers, distributors and retailers, hospitals and government agencies. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in their credit profile. The Company also continues to monitor global economic conditions, including the volatility associated with international sovereign economies, and associated impacts on the financial markets and its business. The Company has accounts receivable factoring agreements with financial institutions in certain countries to sell accounts receivable. The Company factored $2.7 billion and $3.0 billion of accounts receivable as of March 31, 2024 and December 31, 2023, respectively, under these factoring arrangements, which reduced outstanding accounts receivable. The cash received from the financial institutions is reported within operating activities in the Condensed Consolidated Statement of Cash Flows. In certain of these factoring arrangements, for ease of administration, the Company will collect customer payments related to the factored receivables, which it then remits to the financial institutions, generally within thirty days after receipt. As of March 31, 2024 and December 31, 2023, the Company had collected $43 million and $44 million, respectively, on behalf of the financial institutions, which is reflected as restricted cash in Other current assets and the related obligation to remit the cash within Accrued and other current liabilities . The net cash flows related to these collections are reported as financing activities in the Condensed Consolidated Statement of Cash Flows. The cost of factoring such accounts receivable was de minimis . Derivative financial instruments are executed under International Swaps and Derivatives Association master agreements. The master agreements with several of the Company’s financial institution counterparties also include credit support annexes. These annexes contain provisions that require collateral to be exchanged depending on the value of the derivative assets and liabilities, the Company’s credit rating, and the credit rating of the counterparty. Cash collateral received by the Company from various counterparties was $58 million and $3 million at March 31, 2024 and December 31, 2023, respectively. The obligation to return such collateral is recorded in Accrued and other current liabilities

Inventories

Inventories	3 Months Ended
Inventories	Mar. 31, 2024
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of: ($ in millions) March 31, 2024 December 31, 2023 Finished goods $ 1,902 $ 1,954 Raw materials and work in process 8,366 8,037 Supplies 276 277 Total 10,544 10,268 Decrease to LIFO cost (621) (562) $ 9,923 $ 9,706 Recognized as: Inventories $ 6,510 $ 6,358 Other Assets 3,413 3,348 Amounts recognized as Other Assets are comprised almost entirely of raw materials and work in process inventories. At both March 31, 2024 and December 31, 2023, these amounts included $2.6 billion of inventories not expected to be sold within one year. In addition, these amounts included $861 million and $790 million at March 31, 2024 and December 31, 2023, respectively, of inventories produced in preparation for product launches.

Contingencies

Contingencies	3 Months Ended
Contingencies	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is involved in various claims and legal proceedings of a nature considered normal to its business, including product liability, intellectual property, and commercial litigation, as well as certain additional matters including governmental and environmental matters. In the opinion of the Company, it is unlikely that the resolution of these matters will be material to the Company’s financial condition, results of operations or cash flows. Given the nature of the litigation discussed below and the complexities involved in these matters, the Company is unable to reasonably estimate a possible loss or range of possible loss for such matters until the Company knows, among other factors, (i) what claims, if any, will survive dispositive motion practice, (ii) the extent of the claims, including the size of any potential class, particularly when damages are not specified or are indeterminate, (iii) how the discovery process will affect the litigation, (iv) the settlement posture of the other parties to the litigation and (v) any other factors that may have a material effect on the litigation. The Company records accruals for contingencies when it is probable that a liability has been incurred and the amount can be reasonably estimated. These accruals are adjusted periodically as assessments change or additional information becomes available. Generally, for product liability claims, a portion of the overall accrual is actuarially determined and considers such factors as past experience, number of claims reported and estimates of claims incurred but not yet reported. Individually significant contingent losses are accrued when probable and reasonably estimable. Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable. The Company’s decision to obtain insurance coverage is dependent on market conditions, including cost and availability, existing at the time such decisions are made. The Company has evaluated its risks and has determined that the cost of obtaining product liability insurance outweighs the likely benefits of the coverage that is available and, as such, has no insurance for most product liabilities. Product Liability Litigation Dr. Scholl’s Foot Powder Merck is a defendant in product liability lawsuits in the U.S. arising from consumers’ alleged exposure to talc in Dr. Scholl’s foot powder, which Merck acquired through its merger with Schering-Plough Corporation and sold as part of the divestiture of Merck’s consumer care business to Bayer in 2014. In these actions, plaintiffs allege that they were exposed to asbestos-contaminated talc and developed mesothelioma as a result. As of March 31, 2024, approximately 275 cases were pending against Merck in various state courts. Gardasil/Gardasil 9 As previously disclosed, Merck is a defendant in product liability lawsuits in the U.S. involving Gardasil (Human Papillomavirus Quadrivalent [Types 6, 11, 16 and 18] Vaccine, Recombinant) and Gardasil 9 (Human Papillomavirus 9-valent Vaccine, Recombinant). As of March 31, 2024, approximately 190 cases were filed and pending against Merck in either federal or state court. In these actions, plaintiffs allege, among other things, that they suffered various personal injuries after vaccination with Gardasil or Gardasil 9, with postural orthostatic tachycardia syndrome as a predominate alleged injury. In August 2022, the U.S. Judicial Panel on Multidistrict Litigation ordered that Gardasil/Gardasil 9 product liability cases pending in federal courts nationwide be transferred to Judge Robert J. Conrad in the Western District of North Carolina for coordinated pre-trial proceedings. In February 2024, the multidistrict litigation was reassigned to Judge Kenneth D. Bell. There are fewer than 15 product liability cases pending outside the U.S. Governmental Proceedings As previously disclosed, from time to time, the Company’s subsidiaries in China receive inquiries regarding their operations from various Chinese governmental agencies. Some of these inquiries may be related to matters involving other multinational pharmaceutical companies, as well as Chinese entities doing business with such companies. The Company’s policy is to cooperate with these authorities and to provide responses as appropriate. As previously disclosed, from time to time, the Company receives inquiries and is the subject of preliminary investigation activities from competition and other governmental authorities in markets outside the U.S. These authorities may include regulators, administrative authorities, and law enforcement and other similar officials, and these preliminary investigation activities may include site visits, formal or informal requests or demands for documents or materials, inquiries or interviews and similar matters. Certain of these preliminary inquiries or activities may lead to the commencement of formal proceedings. Should those proceedings be determined adversely to the Company, monetary fines and/or remedial undertakings may be required. Commercial and Other Litigation Zetia Antitrust Litigation As previously disclosed, Merck, Merck Sharp & Dohme, LLC. (MSD), Schering Corporation, Schering-Plough Corporation, and MSP Singapore Company LLC (collectively, the Merck Defendants) were defendants in a number of lawsuits filed in 2018 on behalf of direct and indirect purchasers of Zetia alleging violations of federal and state antitrust laws, as well as other state statutory and common law causes of action. The cases were consolidated in a federal multidistrict litigation (the Zetia MDL) before Judge Rebecca Beach Smith in the Eastern District of Virginia. As previously disclosed, in April 2023, the Merck Defendants reached settlements with the direct purchaser and retailer plaintiffs and a proposed settlement, subject to court approval, with the indirect purchaser class. Under these agreements, Merck agreed to pay $572.5 million to resolve the direct purchaser, retailer, and indirect purchaser plaintiffs’ claims, which was recorded as an expense in the Company’s financial results in the first quarter of 2023. In October 2023, the court granted final approval of the indirect purchaser class settlement. In 2020 and 2021, United Healthcare Services, Inc. (United Healthcare), Humana Inc. (Humana), Centene Corporation and others (Centene), and Kaiser Foundation Health Plan, Inc. (Kaiser) (collectively, the Insurer Plaintiffs), each filed a lawsuit in a jurisdiction outside of the Eastern District of Virginia against the Merck Defendants and others, making similar allegations as those made in the Zetia MDL, as well as additional allegations about Vytorin. These cases were transferred to the Eastern District of Virginia to proceed with the Zetia MDL. In February 2022, the Insurer Plaintiffs filed amended complaints. In March 2022, the Merck Defendants, jointly with other defendants, moved to dismiss certain aspects of the Insurer Plaintiffs’ complaints, including any claims for Vytorin damages. In December 2023, prior to a decision on the motion to dismiss, the U.S. Judicial Panel on Multidistrict Litigation remanded the four Insurer Plaintiff cases to the transferor courts in the Northern District of California (Kaiser), the District of Minnesota (United Healthcare), and the District of New Jersey (Humana and Centene). On March 15, 2024, the Merck Defendants filed motions to dismiss the Humana and Centene cases. Qui Tam Litigation As previously disclosed, in June 2012, the U.S. District Court for the Eastern District of Pennsylvania unsealed a complaint that had been filed against the Company under the federal False Claims Act by two former employees alleging, among other things, that the Company defrauded the U.S. government by falsifying data in connection with a clinical study conducted on the mumps component of the Company’s M-M-R II vaccine. The complaint alleges the fraud took place between 1999 and 2001. The U.S. government had the right to participate in and take over the prosecution of this lawsuit but notified the court that it declined to exercise that right. The two former employees are pursuing the lawsuit without the involvement of the U.S. government. In July 2023, the court denied relators’ motion for summary judgment, granted two of the Company’s motions for summary judgment, and denied the Company’s remaining motions for summary judgment as moot. The court entered judgment in favor of the Company and dismissed relators’ amended complaint in full with prejudice. Relators have appealed that decision. In addition, as previously disclosed, two putative class action lawsuits on behalf of direct purchasers of the M-M-R II vaccine, which charge that the Company misrepresented the efficacy of the M-M-R II vaccine in violation of federal antitrust laws and various state consumer protection laws, are pending in the Eastern District of Pennsylvania. In the antitrust case, the court granted the Company’s motion for summary judgment as to plaintiffs’ state law claims and denied the motion as to plaintiffs’ antitrust claim. The Company has appealed the antitrust decision. Patent Litigation From time to time, generic manufacturers of pharmaceutical products file abbreviated New Drug Applications (ANDAs) with the U.S. Food and Drug Administration (FDA) seeking to market generic forms of the Company’s products prior to the expiration of relevant patents owned by the Company. To protect its patent rights, the Company may file patent infringement lawsuits against such generic companies. Similar lawsuits defending the Company’s patent rights may exist in other countries. The Company intends to vigorously defend its patents, which it believes are valid, against infringement by companies attempting to market products prior to the expiration of such patents. As with any litigation, there can be no assurance of the outcomes, which, if adverse, could result in significantly shortened periods of exclusivity for these products and, with respect to products acquired through acquisitions accounted for as business combinations, potentially significant intangible asset impairment charges. Bridion — As previously disclosed, between January and November 2020, the Company received multiple Paragraph IV Certification Letters under the Hatch-Waxman Act notifying the Company that generic drug companies had filed applications to the FDA seeking pre-patent expiry approval to sell generic versions of Bridion (sugammadex) Injection. In March, April and December 2020, the Company filed patent infringement lawsuits in the U.S. District Courts for the District of New Jersey and the Northern District of West Virginia against those generic companies. All actions in the District of New Jersey were consolidated. The West Virginia case was jointly dismissed with prejudice in August 2022 in favor of proceeding in New Jersey. The remaining defendants in the New Jersey action stipulated to infringement of the asserted claims and withdrew all remaining claims and defenses other than a defense seeking to shorten the patent term extension (PTE) of the sugammadex patent to December 2022. The U.S. District Court for the District of New Jersey held a one-day trial in December 2022 on this remaining PTE calculation defense. As previously disclosed, in June 2023, the U.S. District Court for the District of New Jersey ruled in Merck’s favor. The court held that Merck’s calculation of PTE for the sugammadex patent covering the compound is not invalid and that the U.S. Patent & Trademark Office correctly granted a full five-year extension. This ruling affirms and validates Merck’s U.S. patent protection for Bridion through at least January 2026. Also in June 2023, the U.S. District Court for the District of New Jersey issued a final judgment prohibiting the FDA from approving any of the pending or tentatively approved generic applications until January 27, 2026, except for any subsequent agreements between defendants and Merck or further order by the court. In July 2023, defendants filed a notice of appeal with the U.S. Court of Appeals for the Federal Circuit. The appeal is currently pending. While the New Jersey action was pending, the Company settled with five generic companies providing that these generic companies can bring their generic versions of Bridion to the market in January 2026 (which may be delayed by any applicable pediatric exclusivity) or earlier under certain circumstances. The Company agreed to stay the lawsuit filed against two generic companies, which in exchange agreed to be bound by a judgment on the merits of the consolidated action in the District of New Jersey. One of the generic companies in the consolidated action requested dismissal of the action against it and the Company did not oppose this request, which was subsequently granted by the court. The Company does not expect this company to bring its generic version of Bridion to the market before January 2026 or later, depending on any applicable pediatric exclusivity. On February 5, 2024, the Company received another Paragraph IV Certification Letter under the Hatch-Waxman Act notifying the Company that Hikma Pharmaceuticals USA Inc. has filed an application to the FDA seeking pre-patent expiry approval to sell a generic version of Bridion Injection. On March 15, 2024, the Company filed a patent infringement lawsuit in the U.S. District Court for the District of New Jersey against Hikma, postponing FDA approval of the Hikma generic drug for 30 months or until expiration of the sugammadex patent (January 27, 2026) and any potentially applicable pediatric exclusivity or an adverse court decision, if any, whichever may occur earlier. Expiration of the patent, and any potentially applicable pediatric exclusivity, will occur earlier than expiry of the 30-month stay. Januvia, Janumet, Janumet XR — As previously disclosed, the FDA granted pediatric exclusivity with respect to Januvia (sitagliptin), Janumet (sitagliptin/metformin HCI), and Janumet XR (sitagliptin and metformin HCl extended-release), which provides a further six months of exclusivity in the U.S. beyond the expiration of all patents listed in the FDA’s Orange Book. Adding this exclusivity to the term of the key patent protection extended exclusivity on these products to January 2023. However, Januvia , Janumet , and Janumet XR contain sitagliptin phosphate monohydrate and the Company has another patent covering certain phosphate salt and polymorphic forms of sitagliptin that expires in May 2027, including pediatric exclusivity (2027 salt/polymorph patent). As previously disclosed, beginning in 2019, a number of generic drug companies filed ANDAs seeking approval of generic forms of Januvia and Janumet along with paragraph IV certifications challenging the validity of the 2027 salt/polymorph patent. The Company responded by filing infringement suits which have all been settled. The Company has settled with a total of 26 generic companies providing that these generic companies can bring their generic versions of Januvia and Janumet to the market in the U.S. in May 2026 or earlier under certain circumstances, and their generic versions of Janumet XR to the market in July 2026 or earlier under certain circumstances. In March 2021, the Company filed a patent infringement lawsuit in the U.S. District Court for the District of Delaware against Zydus Worldwide DMCC, Zydus Pharmaceuticals (USA) Inc., and Cadila Healthcare Ltd. (collectively, Zydus). In that lawsuit, the Company alleged infringement of the 2027 salt/polymorph patent based on the filing of Zydus’s NDA seeking approval of a form of sitagliptin that is a different form than that used in Januvia . In December 2022, the parties reached settlement that included dismissal of the case without prejudice enabling Zydus to seek final approval of a non-automatically substitutable product. In January 2023, the Company received a Paragraph IV Certification Letter under the Hatch-Waxman Act notifying the Company that Zydus filed an ANDA seeking approval of sitagliptin/metformin HCl tablets and certifying that no valid or enforceable claim of any of the patents listed in FDA’s Orange Book for Janumet will be infringed by the proposed Zydus product. In March 2023, the parties reached settlement enabling Zydus to seek final approval of a non-automatically substitutable product containing a different form of sitagliptin than that used in Janumet. In November 2023, the Company received a Paragraph IV Certification Letter under the Hatch-Waxman Act notifying the Company that Zydus filed an ANDA seeking approval of sitagliptin/metformin HCl Extended Release tablets. In January 2024, the parties reached settlement enabling Zydus to seek final approval of a non-automatically substitutable version containing a different form of sitagliptin than that used in Janumet XR . As a result of these settlement agreements related to the later expiring 2027 salt/polymorph patent directed to the specific sitagliptin salt form of the products, the Company expects that Januvia and Janumet will not lose market exclusivity in the U.S. until May 2026 and Janumet XR will not lose market exclusivity in the U.S. until July 2026 , although Zydus has received FDA approval for a non-automatically substitutable form of sitagliptin that differs from the form in the Company’s sitagliptin products . Supplementary Protection Certificates (SPCs) for Janumet expired in April 2023 for the majority of European countries. Prior to expiration, generic companies sought revocation of the Janumet SPCs in a number of European countries. In February 2022, a Finnish court referred certain questions to the Court of Justice of the European Union (CJEU) that could determine the validity of the Janumet SPCs in Europe, for which an oral hearing was held in March 2023 and an Advocate General Opinion is expected in June 2024 with a decision later in 2024. If the CJEU renders a decision that negatively impacts the validity of the Janumet SPCs throughout Europe, generic companies that were prevented from launching products during the SPC period in certain European countries may have an action for damages. Those countries include Belgium, Czech Republic, Ireland, Finland, France, Slovakia and Switzerland. If the Janumet SPCs are ultimately upheld, the Company has reserved its rights related to the pursuit of damages for those countries where a generic launched prior to expiry of the Janumet SPC. In October 2023, the Company filed a patent infringement lawsuit against Sawai Pharmaceuticals Co., Ltd. and Medisa Shinyaku Co., Ltd (collectively, Defendants) in the Tokyo District Court seeking an injunction to stop the manufacture, sale and offer for sale of the Defendants’ sitagliptin dihydrogen phosphate product, while the Company’s patents and patent term extensions are in force. The lawsuit is in response to the Defendants’ application for marketing authorization to sell a generic sitagliptin dihydrogen phosphate product, in the anhydrate form, which was approved on August 15, 2023. Merck asserts that the Defendants’ activity infringes a patent term extension associated with Merck’s patent directed to the sitagliptin compound patent. Keytruda — As previously disclosed, in November 2022, the Company filed a complaint against The Johns Hopkins University (JHU) in the U.S. District Court of Maryland. This action concerns patents emerging from a joint research collaboration between Merck and JHU regarding the use of pembrolizumab, which Merck sells under the trade name Keytruda . Merck and JHU partnered to design and conduct a clinical study administering Keytruda to cancer patients having tumors that had the genetic biomarker known as microsatellite instability-high (MSI-H). After the conclusion of the study, JHU secured U.S. patents citing the joint research study. Merck alleges that JHU has breached the collaboration agreement by filing and obtaining these patents without informing or involving Merck and then licensing the patents to others. Merck therefore brought this action for breach of contract, declaratory judgment of noninfringement, and promissory estoppel. JHU answered the complaint in April and May 2023, denying Merck’s claims, and counterclaiming for willful infringement of nine issued U.S. patents, including a demand for damages. Between November 30, 2023, and March 13, 2024, the Company filed inter partes review petitions with the United States Patent & Trademark Office Patent Trial and Appeal Board, challenging the validity of all nine patents asserted in the case. Lynparza — In December 2022, AstraZeneca Pharmaceuticals LP received a Paragraph IV Certification Letter under the Hatch-Waxman Act notifying AstraZeneca that Natco Pharma Limited (Natco) has filed an application to the FDA seeking pre-patent expiry approval to sell generic versions of Lynparza (olaparib) tablet. In February 2023, AstraZeneca and the Company filed a patent infringement lawsuit in the U.S. District Court for the District of New Jersey/Delaware against Natco. This lawsuit, which asserts one or more patents covering olaparib, automatically stays FDA approval of the generic application until June 2025 or until an adverse court decision, if any, whichever may occur earlier. In December 2023, AstraZeneca Pharmaceuticals LP received a second Paragraph IV Certification Letter under the Hatch-Waxman Act notifying AstraZeneca that Sandoz Inc. has filed an application to the FDA seeking pre-patent expiry approval to sell generic versions of Lynparza (olaparib) tablet. In February 2024, AstraZeneca and the Company filed a patent infringement lawsuit in the U.S. District Court for the District of New Jersey against Sandoz. This lawsuit, which asserts one or more patents covering olaparib, automatically stays FDA approval of the generic application until June 2026 or until an adverse court decision, if any, whichever may occur earlier. Other Litigation There are various other pending legal proceedings involving the Company, principally product liability and intellectual property lawsuits. While it is not feasible to predict the outcome of such proceedings, in the opinion of the Company, either the likelihood of loss is remote or any reasonably possible loss associated with the resolution of such proceedings is not expected to be material to the Company’s financial condition, results of operations or cash flows either individually or in the aggregate. Legal Defense Reserves Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable. Some of the significant factors considered in the review of these legal defense reserves are as follows: the actual costs incurred by the Company; the development of the Company’s legal defense strategy and structure in light of the scope of its litigation; the number of cases being brought against the Company; the costs and outcomes of completed trials; and the most current information regarding anticipated timing, progression, and related costs of pre-trial activities and trials in the associated litigation. The amount of legal defense reserves as of March 31, 2024 and December 31, 2023 of approximately $220 million and $210 million, respectively, represents the Company’s best estimate of the minimum amount of defense costs to be incurred in connection with its outstanding litigation; however, events such as additional trials and other events that could arise in the course of its litigation could affect the ultimate amount of legal defense costs to be incurred by the Company. The Company will continue to monitor its legal defense costs and review the adequacy of the associated reserves and may determine to increase the reserves at any time in the future if, based upon the factors set forth, it believes it would be appropriate to do so.

Equity

Equity	3 Months Ended
Equity	Mar. 31, 2024
Equity [Abstract]
Equity	Equity Three Months Ended March 31, Common Stock Other Retained Accumulated Treasury Stock Non- Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at January 1, 2023 3,577 $ 1,788 $ 44,379 $ 61,081 $ (4,768) 1,039 $ (56,489) $ 67 $ 46,058 Net income attributable to Merck & Co., Inc. — — — 2,821 — — — — 2,821 Other comprehensive loss, net of taxes — — — — (115) — — — (115) Cash dividends declared on common stock ($0.73 per share) — — — (1,863) — — — — (1,863) Treasury stock shares purchased — — — — — 1 (149) — (149) Share-based compensation plans and other — — 88 — — — 61 — 149 Net income attributable to noncontrolling interests — — — — — — — 4 4 Balance at March 31, 2023 3,577 $ 1,788 $ 44,467 $ 62,039 $ (4,883) 1,040 $ (56,577) $ 71 $ 46,905 Balance at January 1, 2024 3,577 $ 1,788 $ 44,509 $ 53,895 $ (5,161) 1,045 $ (57,450) $ 54 $ 37,635 Net income attributable to Merck & Co., Inc. — — — 4,762 — — — — 4,762 Other comprehensive loss, net of taxes — — — — (113) — — — (113) Cash dividends declared on common stock ($0.77 per share) — — — (1,960) — — — — (1,960) Treasury stock shares purchased — — — — — 1 (122) — (122) Share-based compensation plans and other — — 89 — — (2) 127 1 217 Net income attributable to noncontrolling interests — — — — — — — 5 5 Balance at March 31, 2024 3,577 $ 1,788 $ 44,598 $ 56,697 $ (5,274) 1,044 $ (57,445) $ 60 $ 40,424

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	3 Months Ended
Pension and Other Postretirement Benefit Plans	Mar. 31, 2024
Retirement Benefits [Abstract]
Pension and Other Postretirement Benefit Plans	Pension and Other Postretirement Benefit Plans The Company has defined benefit pension plans covering eligible employees in the U.S. and in certain of its international subsidiaries. The net periodic benefit cost (credit) of such plans consisted of the following components: Three Months Ended 2024 2023 ($ in millions) U.S. International U.S. International Service cost $ 86 $ 61 $ 76 $ 49 Interest cost 134 74 133 74 Expected return on plan assets (207) (139) (187) (128) Amortization of unrecognized prior service credit — (3) — (3) Net loss (gain) amortization 10 1 — (1) Termination benefits 3 — — — Curtailments — — 2 — Settlements — — 21 — $ 26 $ (6) $ 45 $ (9) The Company provides medical benefits, principally to its eligible U.S. retirees and similar benefits to their dependents, through its other postretirement benefit plans. The net credit of such plans consisted of the following components: Three Months Ended ($ in millions) 2024 2023 Service cost $ 8 $ 8 Interest cost 14 16 Expected return on plan assets (20) (16) Amortization of unrecognized prior service credit (11) (12) Net gain amortization (12) (11) $ (21) $ (15) In connection with restructuring actions (see Note 4), termination charges were recorded on pension plans related to expanded eligibility for certain employees e x iting Merck. Also, in connection with these restructuring activities, curtailments were recorded on certain pension plans. In addition, lump sum payments to U.S. pension plan participants triggered a partial settlement resulting in a charge of $21 million in the first quarter of 2023. This partial settlement triggered a remeasurement of some of the Company’s U.S. pension plans. The remeasurement, which was calculated using discount rates and asset values as of March 31, 2023, resulted in a net increase of $44 million to net pension liabilities and also resulted in a related adjustment to AOCL . The components of net periodic benefit cost (credit) other than the service cost component are included in Other (income) expense, net (see Note 10), with the exception of certain amounts for termination benefits, curtailments and settlements, which are recorded in Restructuring costs if the event giving rise to the termination benefits, curtailment or settlement related to restructuring actions.

Other (Income) Expense, Net

Other (Income) Expense, Net	3 Months Ended
Other (Income) Expense, Net	Mar. 31, 2024
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net, consisted of: Three Months Ended ($ in millions) 2024 2023 Interest income $ (73) $ (112) Interest expense 303 242 Exchange losses 83 61 Income from investments in equity securities, net (1) (143) (450) Net periodic defined benefit plan (credit) cost other than service cost (160) (115) Other, net (43) 463 $ (33) $ 89 (1) Includes net realized and unrealized gains and losses from investments in equity securities either owned directly or through ownership interests in investment funds. Unrealized gains and losses from investments that are directly owned are determined at the end of the reporting period, while gains and losses from ownership interests in investment funds are accounted for on a one quarter lag. Other, net (as reflected in the table above) in the first three months of 2023 includes a $572.5 million charge related to settlements with certain plaintiffs in the Zetia antitrust litigation (see Note 7). Interest paid for the three months ended March 31, 2024 and 2023 was $217 million and $208 million, respectively.

Income Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective income tax rate of 15.9% for the first quarter of 2024 reflects a 1.6 percentage point unfavorable discrete impact of a charge for the acquisition of Harpoon for which no tax benefit was recognized. The effective income tax rate of 22.6% for the first quarter of 2023 reflects a 5.5 percentage point unfavorable discrete impact of a charge for the acquisition of Imago for which no tax benefit was recognized. The Internal Revenue Service (IRS) is currently conducting examinations of the Company’s tax returns for the years 2017 and 2018, including the one-time transition tax enacted under the Tax Cuts and Jobs Act of 2017. If the IRS disagrees with the Company’s transition tax position, it may result in a significant tax liability. The statute of limitations for assessments with respect to the 2019 and 2020 federal return years will expire in June and October of 2024, respectively, unless extended.

Earnings Per Share

Earnings Per Share	3 Months Ended
Earnings Per Share	Mar. 31, 2024
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The calculations of earnings per share are as follows: Three Months Ended ($ and shares in millions except per share amounts) 2024 2023 Net Income Attributable to Merck & Co., Inc. $ 4,762 $ 2,821 Average common shares outstanding 2,533 2,538 Common shares issuable (1) 11 13 Average common shares outstanding assuming dilution 2,544 2,551 Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders $ 1.88 $ 1.11 Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders $ 1.87 $ 1.11 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	3 Months Ended
Other Comprehensive Income (Loss)	Mar. 31, 2024
Equity [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Changes in each component of other comprehensive income (loss) are as follows: Three Months Ended March 31, ($ in millions) Derivatives Employee Foreign Currency Accumulated Other Balance January 1, 2023, net of taxes $ 73 $ (2,408) $ (2,433) $ (4,768) Other comprehensive income (loss) before reclassification adjustments, pretax (66) (47) 79 (34) Tax 14 2 (20) (4) Other comprehensive income (loss) before reclassification adjustments, net of taxes (52) (45) 59 (38) Reclassification adjustments, pretax (102) (1) (7) (2) 9 (100) Tax 21 2 — 23 Reclassification adjustments, net of taxes (81) (5) 9 (77) Other comprehensive income (loss), net of taxes (133) (50) 68 (115) Balance March 31, 2023, net of taxes $ (60) $ (2,458) $ (2,365) $ (4,883) Balance January 1, 2024, net of taxes $ (24) $ (2,793) $ (2,344) $ (5,161) Other comprehensive income (loss) before reclassification adjustments, pretax 209 5 (225) (11) Tax (44) (4) (13) (61) Other comprehensive income (loss) before reclassification adjustments, net of taxes 165 1 (238) (72) Reclassification adjustments, pretax (44) (1) (15) (2) — (59) Tax 9 9 — 18 Reclassification adjustments, net of taxes (35) (6) — (41) Other comprehensive income (loss), net of taxes 130 (5) (238) (113) Balance March 31, 2024, net of taxes $ 106 $ (2,798) $ (2,582) $ (5,274) (1) Primarily relates to foreign currency cash flow hedges that were reclassified from AOCL to Sales . (2) Includes net amortization of prior service cost, actuarial gains and losses, settlements and curtailments included in net periodic benefit cost (see Note 9).

Segment Reporting

Segment Reporting	3 Months Ended
Segment Reporting	Mar. 31, 2024
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s operations are principally managed on a product basis and include two operating segments, Pharmaceutical and Animal Health, both of which are reportable segments. The Pharmaceutical segment includes human health pharmaceutical and vaccine products. Human health pharmaceutical products consist of therapeutic and preventive agents, generally sold by prescription, for the treatment of human disorders. The Company sells these human health pharmaceutical products primarily to drug wholesalers and retailers, hospitals, government agencies and managed health care providers such as health maintenance organizations, pharmacy benefit managers and other institutions. Human health vaccine products consist of preventive pediatric, adolescent and adult vaccines. The Company sells these human health vaccines primarily to physicians, wholesalers, distributors and government entities. A large component of pediatric and adolescent vaccine sales are made to the U.S. Centers for Disease Control and Prevention Vaccines for Children program, which is funded by the U.S. government. Additionally, the Company sells vaccines to the Federal government for placement into vaccine stockpiles. The Animal Health segment discovers, develops, manufactures and markets a wide range of veterinary pharmaceutical and vaccine products, as well as health management solutions and services, for the prevention, treatment and control of disease in all major livestock and companion animal species. The Company also offers an extensive suite of digitally connected identification, traceability and monitoring products. The Company sells its products to veterinarians, distributors, animal producers, farmers and pet owners. Sales of the Company’s products were as follows: Three Months Ended March 31, 2024 2023 ($ in millions) U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 4,119 $ 2,828 $ 6,947 $ 3,485 $ 2,310 $ 5,795 Alliance revenue-Lynparza (1) 135 157 292 142 133 275 Alliance revenue-Lenvima (1) 173 82 255 153 79 232 Welireg 77 7 85 41 1 42 Alliance revenue-Reblozyl (2) 58 12 71 30 12 43 Vaccines Gardasil/Gardasil 9 488 1,761 2,249 416 1,556 1,972 ProQuad/M-M-R II /Varivax 438 133 570 421 107 528 Vaxneuvance 161 58 219 94 13 106 RotaTeq 149 67 216 180 117 297 Pneumovax 23 6 55 61 40 56 96 Hospital Acute Care Bridion 329 111 440 276 210 487 Prevymis 74 100 174 54 75 129 Dificid 68 5 73 62 3 65 Zerbaxa 33 23 56 27 23 50 Noxafil 8 48 56 14 46 60 Cardiovascular Alliance revenue-Adempas/Verquvo (3) 90 8 98 83 16 99 Adempas — 70 70 — 59 59 Virology Lagevrio 45 305 350 (2) 394 392 Isentress/Isentress HD 50 61 111 52 71 123 Delstrigo 12 44 56 11 33 44 Pifeltro 29 13 42 24 10 34 Neuroscience Belsomra 15 32 46 16 40 56 Immunology Simponi — 184 184 — 180 180 Remicade — 39 39 — 51 51 Diabetes Januvia 183 236 419 271 280 551 Janumet 39 212 251 56 272 329 Other pharmaceutical (4) 157 419 576 171 457 626 Total Pharmaceutical segment sales 6,936 7,070 14,006 6,117 6,604 12,721 Animal Health: Livestock 166 683 850 174 676 849 Companion Animal 308 354 661 308 334 642 Total Animal Health segment sales 474 1,037 1,511 482 1,010 1,491 Total segment sales 7,410 8,107 15,517 6,599 7,614 14,212 Other (5) 68 190 258 60 214 275 $ 7,478 $ 8,297 $ 15,775 $ 6,659 $ 7,828 $ 14,487 U.S. plus international may not equal total due to rounding. (1) Alliance revenue for Lynparza and Lenvima represents Merck’s share of profits, which are product sales net of cost of sales and commercialization costs (see Note 3). (2) Alliance revenue for Reblozyl represents royalties (see Note 3). (3) Alliance revenue for Adempas/Verquvo represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs (see Note 3). (4) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (5) Other is primarily comprised of miscellaneous corporate revenue, including revenue hedging activities which increased sales by $54 million and $99 million for the three months ended March 31, 2024 and 2023, respectively, as well as revenue from third-party manufacturing arrangements (including sales to Organon). Other for the three months ended March 31, 2024 and 2023 also includes $61 million and $51 million, respectively, related to upfront and milestone payments received by Merck for out-licensing arrangements. Product sales are recorded net of the provision for discounts, including chargebacks, which are customer discounts that occur when a contracted customer purchases through an intermediary wholesale purchaser, and rebates that are owed based upon definitive contractual agreements or legal requirements with private sector and public sector (Medicaid and Medicare Part D) benefit providers, after the final dispensing of the product by a pharmacy to a benefit plan participant. These discounts, in the aggregate, reduced U.S. sales by $3.2 billion and $3.1 billion for the three months ended March 31, 2024 and 2023, respectively. Consolidated sales by geographic area where derived are as follows: Three Months Ended ($ in millions) 2024 2023 United States $ 7,478 $ 6,659 Europe, Middle East and Africa 3,563 3,303 China 1,772 1,715 Japan 821 758 Latin America 796 661 Asia Pacific (other than China and Japan) 724 846 Other 621 545 $ 15,775 $ 14,487 A reconciliation of segment profits to Income Before Taxes is as follows: Three Months Ended ($ in millions) 2024 2023 Segment profits: Pharmaceutical segment $ 10,904 $ 9,140 Animal Health segment 555 566 Total segment profits 11,459 9,706 Other profits 146 164 Unallocated: Interest income 73 112 Interest expense (303) (242) Amortization (473) (543) Depreciation (452) (398) Research and development (3,851) (4,147) Restructuring costs (123) (67) Charge for Zetia antitrust litigation settlements — (573) Other unallocated, net (806) (362) $ 5,670 $ 3,650 Pharmaceutical segment profits are comprised of segment sales less standard costs, as well as selling, general and administrative expenses directly incurred by the segment. Animal Health segment profits are comprised of segment sales, less all cost of sales, as well as selling, general and administrative expenses and research and development costs directly incurred by the segment. For internal management reporting presented to the chief operating decision maker, Merck does not allocate the remaining cost of sales not included in segment profits as described above, research and development expenses incurred by Merck Research Laboratories, the Company’s research and development division that focuses on human health-related activities, or general and administrative expenses not directly incurred by the segments, nor the cost of financing these activities. Separate divisions maintain responsibility for monitoring and managing these costs, including depreciation related to fixed assets utilized by these divisions and, therefore, they are not included in segment profits. In addition, costs related to restructuring activities, as well as the amortization of intangible assets and amortization of purchase accounting adjustments are not allocated to segments. Other profits are primarily comprised of miscellaneous corporate profits, as well as operating profits (losses) related to third-party manufacturing arrangements. Other unallocated, net, includes expenses from corporate and manufacturing cost centers, intangible asset impairment charges, gains or losses on sales of businesses, expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration, and other miscellaneous income or expense items.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Millions	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income Attributable to Merck & Co., Inc.	$ 4,762	$ 2,821

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Merck & Co., Inc. (Merck or the Company) have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the United States (U.S.) for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited financial statements and notes thereto included in Merck’s Form 10-K filed on February 26, 2024.
Reclassifications	Certain reclassifications have been made to prior year amounts to conform to the current year presentation.
Recently Issued Accounting Standard Not Yet Adopted	Recently Issued Accounting Standards Not Yet Adopted In August 2023, the Financial Accounting Standards Board (FASB) issued amended guidance that requires a newly formed joint venture to recognize and initially measure its assets and liabilities at fair value upon formation. The amended guidance includes exceptions to fair value measurement that are consistent with the accounting for business combinations guidance. The amended guidance is effective prospectively for all joint ventures with a formation date on or after January 1, 2025, however existing joint ventures have the option to apply the guidance retrospectively. Early adoption is permitted for both interim and annual periods. The Company anticipates there will be no impact to its consolidated financial statements upon adoption. In November 2023, the FASB issued guidance intended to improve reportable segment disclosure requirements, primarily through expanded disclosures for significant segment expenses. The guidance is effective for annual periods beginning in 2024, and interim periods beginning in 2025. The guidance will result in incremental disclosures within the footnotes to the Company’s financial statements.
Legal Costs	Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable.

Collaborative Arrangements (Tab

Collaborative Arrangements (Tables)	3 Months Ended
Collaborative Arrangements (Tables)	Mar. 31, 2024
Collaborative Arrangements [Abstract]
Collaboration Arrangements	Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Alliance revenue - Lynparza $ 292 $ 275 Alliance revenue - Koselugo 38 23 Total alliance revenue $ 330 $ 298 Cost of sales (1) 82 70 Selling, general and administrative 39 47 Research and development 20 21 ($ in millions) March 31, 2024 December 31, 2023 Receivables from AstraZeneca included in Other current assets $ 334 $ 341 Payables to AstraZeneca included in Accrued and other current liabilities (2) 617 256 Payables to AstraZeneca included in Other Noncurrent Liabilities (2) — 600 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone payments. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Alliance revenue - Lenvima $ 255 $ 232 Cost of sales (1) 60 126 Selling, general and administrative 39 51 Research and development 8 39 ($ in millions) March 31, 2024 December 31, 2023 Receivables from Eisai included in Other current assets $ 255 $ 226 Payables to Eisai included in Accrued and other current liabilities (2) 125 125 (1) Represents amortization of capitalized milestone payments. Amount in the first quarter of 2023 includes $72 million of cumulative amortization catch-up expense as noted above. (2) Represents an accrued milestone payment. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Alliance revenue - Adempas/Verquvo $ 98 $ 99 Net sales of Adempas recorded by Merck 70 59 Net sales of Verquvo recorded by Merck 5 7 Total sales $ 173 $ 165 Cost of sales (1) 62 57 Selling, general and administrative 33 33 Research and development 28 25 ($ in millions) March 31, 2024 December 31, 2023 Receivables from Bayer included in Other current assets $ 155 $ 156 Payables to Bayer included in Accrued and other current liabilities 74 80 (1) Includes amortization of intangible assets, cost of products sold by Merck, as well as Bayer’s share of profits from sales in Merck’s marketing territories. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Net sales of Lagevrio recorded by Merck $ 350 $ 392 Cost of sales (1) 191 221 Selling, general and administrative 16 27 Research and development (5) 16 ($ in millions) March 31, 2024 December 31, 2023 Payables to Ridgeback included in Accrued and other current liabilities (2) $ 160 $ 113 (1) Includes cost of products sold by Merck, Ridgeback’s share of profits, royalty expense, amortization of capitalized milestone payments and inventory reserves. (2) Includes accrued royalties. Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Selling, general and administrative $ 3 $ — Research and development 69 — ($ in millions) March 31, 2024 December 31, 2023 Payables to Daiichi Sankyo included in Accrued and other current liabilities $ 817 $ 800 Payables to Daiichi Sankyo included in Other Noncurrent Liabilities 750 750 Summarized financial information related to this collaboration is as follows: Three Months Ended ($ in millions) 2024 2023 Selling, general and administrative $ 2 $ 1 Research and development 69 26 ($ in millions) March 31, 2024 December 31, 2023 Payables to Moderna included in Accrued and other current liabilities $ 72 $ 63

Restructuring (Tables)

Restructuring (Tables)	3 Months Ended
Restructuring (Tables)	Mar. 31, 2024
Restructuring and Related Activities [Abstract]
Charges Related to Restructuring Program Activities by Type of Cost	The following tables summarize the charges related to the restructuring programs by type of cost: Three Months Ended March 31, 2024 ($ in millions) Accelerated Depreciation Separation Costs Other Exit Costs Total 2024 Restructuring Program Cost of sales $ 65 $ — $ 51 $ 116 Selling, general and administrative — — 5 5 Research and development — — 2 2 Restructuring costs — 92 31 123 $ 65 $ 92 $ 89 $ 246 Three Months Ended March 31, 2023 ($ in millions) Accelerated Depreciation Separation Costs Other Exit Costs Total 2019 Restructuring Program Cost of sales $ 21 $ — $ 8 $ 29 Selling, general and administrative — — 1 1 Restructuring costs — 41 26 67 $ 21 $ 41 $ 35 $ 97
Charges and Spending Relating to Restructuring Activities by Program	The following table summarizes the charges and spending relating to restructuring program activities for the three months ended March 31, 2024: ($ in millions) Accelerated Depreciation Separation Costs Other Exit Costs Total Restructuring reserves January 1, 2024 $ — $ 681 $ 31 $ 712 Expenses 65 92 89 246 (Payments) receipts, net — (67) (32) (99) Non-cash activity (65) — (58) (123) Restructuring reserves March 31, 2024 $ — $ 706 $ 30 $ 736

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
Financial Instruments (Tables)	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Effect of Net Investment Hedges on OCI and the Consolidated Statement of Operations	The effects of the Company’s net investment hedges on OCI and the Condensed Consolidated Statement of Income are shown below: Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) Amount of Pretax Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing Three Months Ended March 31, Three Months Ended March 31, ($ in millions) 2024 2023 2024 2023 Net Investment Hedging Relationships Foreign exchange contracts $ (2) $ 1 $ — $ 1 Euro-denominated notes (62) 52 — — (1) No amounts were reclassified from AOCL into income related to the sale of a subsidiary.
Summary of Interest Rate Swaps Held	At March 31, 2024, the Company was a party to four pay-floating, receive-fixed interest rate swap contracts designated as fair value hedges of a portion of fixed-rate notes as detailed in the table below. March 31, 2024 ($ in millions) Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 4.50% notes due 2033 $ 1,500 4 $ 1,000
Amounts Recorded on Balance Sheet Related to Fair Value Hedges	The table below presents the location of amounts recorded in the Condensed Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase Included in the Carrying Amount ($ in millions) March 31, 2024 December 31, 2023 March 31, 2024 December 31, 2023 Balance Sheet Caption Long-Term Debt $ 1,026 $ 1,056 $ 26 $ 56
Fair Value of Derivatives on a Gross Basis Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments	Presented in the table below is the fair value of derivatives on a gross basis segregated between those derivatives that are designated as hedging instruments and those that are not designated as hedging instruments: March 31, 2024 December 31, 2023 Fair Value of Derivative U.S. Dollar Fair Value of Derivative U.S. Dollar ($ in millions) Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Balance Sheet Caption Interest rate swap contracts Other Assets $ 27 $ — $ 1,000 $ 57 $ — $ 1,000 Foreign exchange contracts Other current assets 175 — 9,082 106 — 6,138 Foreign exchange contracts Other Assets 32 — 2,062 26 — 1,929 Foreign exchange contracts Accrued and other current liabilities — 10 1,076 — 76 3,680 Foreign exchange contracts Other Noncurrent Liabilities — 1 204 — 1 7 234 11 13,424 189 77 12,754 Derivatives Not Designated as Hedging Instruments Balance Sheet Caption Foreign exchange contracts Other current assets 121 — 9,428 153 — 9,693 Foreign exchange contracts Other Assets 2 — 43 — — — Foreign exchange contracts Accrued and other current liabilities — 154 9,282 — 162 8,104 Foreign exchange contracts Other Noncurrent Liabilities — 2 43 — — — 123 156 18,796 153 162 17,797 $ 357 $ 167 $ 32,220 $ 342 $ 239 $ 30,551
Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis	The following table provides information on the Company’s derivative positions subject to these master netting arrangements as if they were presented on a net basis, allowing for the right of offset by counterparty and cash collateral exchanged per the master agreements and related credit support annexes: March 31, 2024 December 31, 2023 ($ in millions) Asset Liability Asset Liability Gross amounts recognized in the condensed consolidated balance sheet $ 357 $ 167 $ 342 $ 239 Gross amounts subject to offset in master netting arrangements not offset in the condensed consolidated balance sheet (111) (111) (215) (215) Cash collateral received (58) — (3) — Net amounts $ 188 $ 56 $ 124 $ 24
Location and Amount of Pretax Gains and Losses of Derivatives	The table below provides information regarding the location and amount of pretax gains and losses of derivatives designated in fair value or cash flow hedging relationships: Three Months Ended March 31, ($ in millions) 2024 2023 2024 2023 2024 2023 Financial Statement Caption in which Effects of Fair Value or Cash Flow Hedges are Recorded Sales Other (income) expense, net (1) Other comprehensive income (loss) $ 15,775 $ 14,487 $ (33) $ 89 $ (113) $ (115) (Gain) loss on fair value hedging relationships: Interest rate swap contracts Hedged items — — (30) — — — Derivatives designated as hedging instruments — — 30 — — — Impact of cash flow hedging relationships: Foreign exchange contracts Amount of gain (loss) recognized in OCI on derivatives — — — — 209 (66) Increase in Sales as a result of AOCL reclassifications 44 101 — — (44) (101) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — — (1) — — Amount of loss recognized in OCI on derivatives — — — — — (1) (1) Interest expense is a component of Other (income) expense, net.
Income Statement Effects of Derivatives Not Designated as Hedging Instruments	The table below provides information regarding the income statement effects of derivatives not designated as hedging instruments: Amount of Derivative Pretax (Gain) Loss Recognized in Income Three Months Ended March 31, ($ in millions) 2024 2023 Derivatives Not Designated as Hedging Instruments Income Statement Caption Foreign exchange contracts (1) Other (income) expense, net $ 65 $ 13 Foreign exchange contracts (2) Sales (10) 2 (1) These derivative contracts primarily mitigate changes in the value of remeasured foreign currency denominated monetary assets and liabilities attributable to changes in foreign currency exchange rates. (2) These derivative contracts serve as economic hedges of forecasted transactions .
Information on Investments in Debt and Equity Securities	Information on investments in debt and equity securities is as follows: March 31, 2024 December 31, 2023 Amortized Gross Unrealized Fair Amortized Gross Unrealized Fair ($ in millions) Gains Losses Gains Losses Commercial paper $ 40 $ — $ — $ 40 $ 252 $ — $ — $ 252 U.S. government and agency securities 77 — — 77 72 — — 72 Corporate notes and bonds — — — — 13 — — 13 Total debt securities $ 117 $ — $ — $ 117 $ 337 $ — $ — $ 337 Publicly traded equity securities (1) 908 764 Total debt and publicly traded equity securities $ 1,025 $ 1,101 (1) Unrealized net gains of $143 million were recorded in Other (income) expense, net in the first quarter of 2024 on equity securities still held at March 31, 2024. Unrealized net gains of $338 million were recorded in Other (income) expense, net in the first quarter of 2023 on equity securities still held at March 31, 2023.
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	Financial assets and liabilities measured at fair value on a recurring basis are summarized below: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ($ in millions) March 31, 2024 December 31, 2023 Assets Investments Commercial paper $ — $ 40 $ — $ 40 $ — $ 252 $ — $ 252 Publicly traded equity securities 280 — — 280 252 — — 252 280 40 — 320 252 252 — 504 Other assets (1) U.S. government and agency securities 77 — — 77 72 — — 72 Corporate notes and bonds — — — — 13 — — 13 Publicly traded equity securities (2) 628 — — 628 512 — — 512 705 — — 705 597 — — 597 Derivative assets (3) Forward exchange contracts — 204 — 204 — 202 — 202 Purchased currency options — 126 — 126 — 83 — 83 Interest rate swaps — 27 — 27 — 57 — 57 — 357 — 357 — 342 — 342 Total assets $ 985 $ 397 $ — $ 1,382 $ 849 $ 594 $ — $ 1,443 Liabilities Other liabilities Contingent consideration $ — $ — $ 226 $ 226 $ — $ — $ 354 $ 354 Derivative liabilities (3) Forward exchange contracts — 149 — 149 — 239 — 239 Written currency options — 18 — 18 — — — — — 167 — 167 — 239 — 239 Total liabilities $ — $ 167 $ 226 $ 393 $ — $ 239 $ 354 $ 593 (1) Investments included in other assets are restricted as to use, including for the payment of benefits under employee benefit plans. (2) Balance at March 31, 2024 includes securities with a fair value of $266 million, which are subject to a contractual sale restriction that expires in July 2024. (3) The fair value determination of derivatives includes the impact of the credit risk of counterparties to the derivatives and the Company’s own credit risk, the effects of which were not significant.
Information About the Changes in Liabilities for Contingent Consideration	Summarized information about the changes in the fair value of liabilities for contingent consideration associated with business combinations is as follows: ($ in millions) 2024 2023 Fair value January 1 $ 354 $ 456 Changes in estimated fair value (1) (2) 14 Payments (126) (117) Fair value March 31 (2) $ 226 $ 353 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at March 31, 2024, includes $133 million of current liabilities, all of which relate to the termination of the Sanofi Pasteur MSD joint venture in 2016. As part of the termination, Merck recorded a liability for contingent future royalty payments of 11.5% on net sales of all Merck products that were previously sold by the joint venture through December 31, 2024. The fair value of this liability is determined utilizing the estimated amount and timing of projected cash flows using a risk-adjusted discount rate to present value the cash flows.

Inventories (Tables)

Inventories (Tables)	3 Months Ended
Inventories (Tables)	Mar. 31, 2024
Inventory Disclosure [Abstract]
Inventory, current	Inventories consisted of: ($ in millions) March 31, 2024 December 31, 2023 Finished goods $ 1,902 $ 1,954 Raw materials and work in process 8,366 8,037 Supplies 276 277 Total 10,544 10,268 Decrease to LIFO cost (621) (562) $ 9,923 $ 9,706 Recognized as: Inventories $ 6,510 $ 6,358 Other Assets 3,413 3,348
Inventory, noncurrent	Inventories consisted of: ($ in millions) March 31, 2024 December 31, 2023 Finished goods $ 1,902 $ 1,954 Raw materials and work in process 8,366 8,037 Supplies 276 277 Total 10,544 10,268 Decrease to LIFO cost (621) (562) $ 9,923 $ 9,706 Recognized as: Inventories $ 6,510 $ 6,358 Other Assets 3,413 3,348

Equity (Tables)

Equity (Tables)	3 Months Ended
Equity (Tables)	Mar. 31, 2024
Equity [Abstract]
Schedule of Equity	Three Months Ended March 31, Common Stock Other Retained Accumulated Treasury Stock Non- Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at January 1, 2023 3,577 $ 1,788 $ 44,379 $ 61,081 $ (4,768) 1,039 $ (56,489) $ 67 $ 46,058 Net income attributable to Merck & Co., Inc. — — — 2,821 — — — — 2,821 Other comprehensive loss, net of taxes — — — — (115) — — — (115) Cash dividends declared on common stock ($0.73 per share) — — — (1,863) — — — — (1,863) Treasury stock shares purchased — — — — — 1 (149) — (149) Share-based compensation plans and other — — 88 — — — 61 — 149 Net income attributable to noncontrolling interests — — — — — — — 4 4 Balance at March 31, 2023 3,577 $ 1,788 $ 44,467 $ 62,039 $ (4,883) 1,040 $ (56,577) $ 71 $ 46,905 Balance at January 1, 2024 3,577 $ 1,788 $ 44,509 $ 53,895 $ (5,161) 1,045 $ (57,450) $ 54 $ 37,635 Net income attributable to Merck & Co., Inc. — — — 4,762 — — — — 4,762 Other comprehensive loss, net of taxes — — — — (113) — — — (113) Cash dividends declared on common stock ($0.77 per share) — — — (1,960) — — — — (1,960) Treasury stock shares purchased — — — — — 1 (122) — (122) Share-based compensation plans and other — — 89 — — (2) 127 1 217 Net income attributable to noncontrolling interests — — — — — — — 5 5 Balance at March 31, 2024 3,577 $ 1,788 $ 44,598 $ 56,697 $ (5,274) 1,044 $ (57,445) $ 60 $ 40,424

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Plans (Tables)	3 Months Ended
Pension and Other Postretirement Benefit Plans (Tables)	Mar. 31, 2024
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net Benefit Costs	The Company has defined benefit pension plans covering eligible employees in the U.S. and in certain of its international subsidiaries. The net periodic benefit cost (credit) of such plans consisted of the following components: Three Months Ended 2024 2023 ($ in millions) U.S. International U.S. International Service cost $ 86 $ 61 $ 76 $ 49 Interest cost 134 74 133 74 Expected return on plan assets (207) (139) (187) (128) Amortization of unrecognized prior service credit — (3) — (3) Net loss (gain) amortization 10 1 — (1) Termination benefits 3 — — — Curtailments — — 2 — Settlements — — 21 — $ 26 $ (6) $ 45 $ (9)
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Net Benefit Costs	The Company provides medical benefits, principally to its eligible U.S. retirees and similar benefits to their dependents, through its other postretirement benefit plans. The net credit of such plans consisted of the following components: Three Months Ended ($ in millions) 2024 2023 Service cost $ 8 $ 8 Interest cost 14 16 Expected return on plan assets (20) (16) Amortization of unrecognized prior service credit (11) (12) Net gain amortization (12) (11) $ (21) $ (15)

Other (Income) Expense, Net (Ta

Other (Income) Expense, Net (Tables)	3 Months Ended
Other (Income) Expense, Net (Tables)	Mar. 31, 2024
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (income) expense, net, consisted of: Three Months Ended ($ in millions) 2024 2023 Interest income $ (73) $ (112) Interest expense 303 242 Exchange losses 83 61 Income from investments in equity securities, net (1) (143) (450) Net periodic defined benefit plan (credit) cost other than service cost (160) (115) Other, net (43) 463 $ (33) $ 89 (1)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
Earnings Per Share (Tables)	Mar. 31, 2024
Earnings Per Share [Abstract]
Calculations of Earnings Per Share	The calculations of earnings per share are as follows: Three Months Ended ($ and shares in millions except per share amounts) 2024 2023 Net Income Attributable to Merck & Co., Inc. $ 4,762 $ 2,821 Average common shares outstanding 2,533 2,538 Common shares issuable (1) 11 13 Average common shares outstanding assuming dilution 2,544 2,551 Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders $ 1.88 $ 1.11 Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders $ 1.87 $ 1.11 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	3 Months Ended
Other Comprehensive Income (Loss) (Tables)	Mar. 31, 2024
Equity [Abstract]
Changes in AOCI by Component	Changes in each component of other comprehensive income (loss) are as follows: Three Months Ended March 31, ($ in millions) Derivatives Employee Foreign Currency Accumulated Other Balance January 1, 2023, net of taxes $ 73 $ (2,408) $ (2,433) $ (4,768) Other comprehensive income (loss) before reclassification adjustments, pretax (66) (47) 79 (34) Tax 14 2 (20) (4) Other comprehensive income (loss) before reclassification adjustments, net of taxes (52) (45) 59 (38) Reclassification adjustments, pretax (102) (1) (7) (2) 9 (100) Tax 21 2 — 23 Reclassification adjustments, net of taxes (81) (5) 9 (77) Other comprehensive income (loss), net of taxes (133) (50) 68 (115) Balance March 31, 2023, net of taxes $ (60) $ (2,458) $ (2,365) $ (4,883) Balance January 1, 2024, net of taxes $ (24) $ (2,793) $ (2,344) $ (5,161) Other comprehensive income (loss) before reclassification adjustments, pretax 209 5 (225) (11) Tax (44) (4) (13) (61) Other comprehensive income (loss) before reclassification adjustments, net of taxes 165 1 (238) (72) Reclassification adjustments, pretax (44) (1) (15) (2) — (59) Tax 9 9 — 18 Reclassification adjustments, net of taxes (35) (6) — (41) Other comprehensive income (loss), net of taxes 130 (5) (238) (113) Balance March 31, 2024, net of taxes $ 106 $ (2,798) $ (2,582) $ (5,274) (1) Primarily relates to foreign currency cash flow hedges that were reclassified from AOCL to Sales . (2) Includes net amortization of prior service cost, actuarial gains and losses, settlements and curtailments included in net periodic benefit cost (see Note 9).

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
Segment Reporting (Tables)	Mar. 31, 2024
Segment Reporting [Abstract]
Sales from Products	Sales of the Company’s products were as follows: Three Months Ended March 31, 2024 2023 ($ in millions) U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 4,119 $ 2,828 $ 6,947 $ 3,485 $ 2,310 $ 5,795 Alliance revenue-Lynparza (1) 135 157 292 142 133 275 Alliance revenue-Lenvima (1) 173 82 255 153 79 232 Welireg 77 7 85 41 1 42 Alliance revenue-Reblozyl (2) 58 12 71 30 12 43 Vaccines Gardasil/Gardasil 9 488 1,761 2,249 416 1,556 1,972 ProQuad/M-M-R II /Varivax 438 133 570 421 107 528 Vaxneuvance 161 58 219 94 13 106 RotaTeq 149 67 216 180 117 297 Pneumovax 23 6 55 61 40 56 96 Hospital Acute Care Bridion 329 111 440 276 210 487 Prevymis 74 100 174 54 75 129 Dificid 68 5 73 62 3 65 Zerbaxa 33 23 56 27 23 50 Noxafil 8 48 56 14 46 60 Cardiovascular Alliance revenue-Adempas/Verquvo (3) 90 8 98 83 16 99 Adempas — 70 70 — 59 59 Virology Lagevrio 45 305 350 (2) 394 392 Isentress/Isentress HD 50 61 111 52 71 123 Delstrigo 12 44 56 11 33 44 Pifeltro 29 13 42 24 10 34 Neuroscience Belsomra 15 32 46 16 40 56 Immunology Simponi — 184 184 — 180 180 Remicade — 39 39 — 51 51 Diabetes Januvia 183 236 419 271 280 551 Janumet 39 212 251 56 272 329 Other pharmaceutical (4) 157 419 576 171 457 626 Total Pharmaceutical segment sales 6,936 7,070 14,006 6,117 6,604 12,721 Animal Health: Livestock 166 683 850 174 676 849 Companion Animal 308 354 661 308 334 642 Total Animal Health segment sales 474 1,037 1,511 482 1,010 1,491 Total segment sales 7,410 8,107 15,517 6,599 7,614 14,212 Other (5) 68 190 258 60 214 275 $ 7,478 $ 8,297 $ 15,775 $ 6,659 $ 7,828 $ 14,487 U.S. plus international may not equal total due to rounding. (1) Alliance revenue for Lynparza and Lenvima represents Merck’s share of profits, which are product sales net of cost of sales and commercialization costs (see Note 3). (2) Alliance revenue for Reblozyl represents royalties (see Note 3). (3) Alliance revenue for Adempas/Verquvo represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs (see Note 3). (4) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (5) Other is primarily comprised of miscellaneous corporate revenue, including revenue hedging activities which increased sales by $54 million and $99 million for the three months ended March 31, 2024 and 2023, respectively, as well as revenue from third-party manufacturing arrangements (including sales to Organon). Other for the three months ended March 31, 2024 and 2023 also includes $61 million and $51 million, respectively, related to upfront and milestone payments received by Merck for out-licensing arrangements.
Consolidated Sales by Geographic Area	Consolidated sales by geographic area where derived are as follows: Three Months Ended ($ in millions) 2024 2023 United States $ 7,478 $ 6,659 Europe, Middle East and Africa 3,563 3,303 China 1,772 1,715 Japan 821 758 Latin America 796 661 Asia Pacific (other than China and Japan) 724 846 Other 621 545 $ 15,775 $ 14,487
Reconciliation of Segment Profits to Income before Taxes	A reconciliation of segment profits to Income Before Taxes is as follows: Three Months Ended ($ in millions) 2024 2023 Segment profits: Pharmaceutical segment $ 10,904 $ 9,140 Animal Health segment 555 566 Total segment profits 11,459 9,706 Other profits 146 164 Unallocated: Interest income 73 112 Interest expense (303) (242) Amortization (473) (543) Depreciation (452) (398) Research and development (3,851) (4,147) Restructuring costs (123) (67) Charge for Zetia antitrust litigation settlements — (573) Other unallocated, net (806) (362) $ 5,670 $ 3,650

Acquisitions, Divestitures, R_2

Acquisitions, Divestitures, Research Collaborations and Licensing Agreements - Narrative (Details) $ in Millions		1 Months Ended		2 Months Ended	3 Months Ended
	Jun. 02, 2021	Mar. 31, 2024 USD ($) jurisdiction	Jan. 31, 2023 USD ($)	Jul. 31, 2024 USD ($)	Mar. 31, 2024 USD ($) jurisdiction	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Oct. 31, 2023 USD ($) candidate	Feb. 28, 2023 candidate
Business Acquisition [Line Items]
Research and development					$ 3,992	$ 4,276
Sales					15,775	14,487
Cost of sales					3,540	3,926
Other current assets		$ 7,950			7,950		$ 8,368
Accrued and other current liabilities		14,102			14,102		15,766
Related Party
Business Acquisition [Line Items]
Other current assets		462			462		632
Accrued and other current liabilities		$ 193			193		$ 598
Manufacturing and Supply Agreements \| Related Party
Business Acquisition [Line Items]
Sales					107	94
Cost of sales					$ 110	107
Minimum \| Manufacturing and Supply Agreements \| Related Party
Business Acquisition [Line Items]
Period of continuing involvement after disposal	4 years
Maximum \| Manufacturing and Supply Agreements \| Related Party
Business Acquisition [Line Items]
Period of continuing involvement after disposal	10 years
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff \| Organon & Co.
Business Acquisition [Line Items]
Number of jurisdictions remaining \| jurisdiction		1			1
Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Business Acquisition [Line Items]
Number of antibody drug conjugates obtained right and obligations \| candidate									7
Upfront payment made to collaborative partner						175
Number of antibody drug conjugates terminated with collaborative partner \| candidate								2
Eligible future contingent development-related payments (up to)								$ 600
Eligible future contingent regulatory milestone payments (up to)								1,600
Eligible future contingent sales-based milestone payments (up to)								$ 3,100
Stock investment in counterparty			$ 100
Elanco Animal Health Incorporated Aqua Business \| Forecast
Business Acquisition [Line Items]
Payment to acquire business				$ 1,300
Harpoon Therapeutics, Inc.
Business Acquisition [Line Items]
Consideration transferred, asset acquisition		$ 765
Asset acquisition, transaction costs		56
Net assets acquired		$ 165
Research and development					$ 656
Imago Bio Sciences, Inc.
Business Acquisition [Line Items]
Consideration transferred, asset acquisition			1,350
Asset acquisition, transaction costs			60
Net assets acquired			$ 219
Research and development						$ 1,200

Collaborative Arrangements - As

Collaborative Arrangements - AstraZeneca PLC - Narrative (Details) - Lynparza - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2022
Other Intangible Assets \| Licenses and Other
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets	$ 1,400
AstraZeneca \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Probable contingent payments			$ 600
Liabilities			$ 600
Eligible future contingent sales-based milestone payments (up to)	2,100
Regulatory milestone payments	245	$ 105
Eligible future contingent regulatory milestone payments (up to)	$ 650

Collaborative Arrangements - _2

Collaborative Arrangements - AstraZeneca PLC (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	$ 3,540	$ 3,926
Selling, general and administrative	2,483	2,479
Research and development	3,992	4,276
Other current assets	31,445		$ 32,168
Accrued and other current liabilities	14,102		15,766
AstraZeneca \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative arrangement	330	298
Cost of sales	82	70
Selling, general and administrative	39	47
Research and development	20	21
Other current assets	334		341
Accrued and other current liabilities	617		256
Other noncurrent liabilities	0		$ 600
AstraZeneca \| Alliance revenue - Lynparza \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative arrangement	292	275
AstraZeneca \| Alliance revenue - Koselugo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative arrangement	$ 38	$ 23

Collaborative Arrangements - Ei

Collaborative Arrangements - Eisai Co., Ltd. - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Mar. 31, 2024
Alliance revenue - Lenvima \| Other Intangible Assets \| Licenses and Other
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets				$ 623
Eisai
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amortization of intangible assets	$ 81		$ 72
Eisai \| Alliance revenue - Lenvima \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Probable contingent payments	125		$ 125
Liabilities	$ 250			125
Sales-based milestone payments		$ 125
Eligible future contingent sales-based milestone payments (up to)				$ 2,300

Collaborative Arrangements - _3

Collaborative Arrangements - Eisai Co., Ltd. (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Sep. 30, 2023	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	$ 3,540		$ 3,926
Selling, general and administrative	2,483		2,479
Research and development	3,992		4,276
Other current assets	31,445			$ 32,168
Accrued and other current liabilities	14,102			15,766
Eisai
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amortization of intangible assets		$ 81	72
Eisai \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative arrangement	255		232
Cost of sales	60		126
Selling, general and administrative	39		51
Research and development	8		$ 39
Other current assets	255			226
Accrued and other current liabilities	$ 125			$ 125

Collaborative Arrangements - Ba

Collaborative Arrangements - Bayer AG (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	$ 15,775	$ 14,487
Cost of sales	3,540	3,926
Selling, general and administrative	2,483	2,479
Research and development	3,992	4,276
Other current assets	31,445		$ 32,168
Accrued and other current liabilities	14,102		15,766
Bayer AG \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Eligible future contingent sales-based milestone payments (up to)	0
Revenue from collaborative arrangement	98	99
Sales	173	165
Cost of sales	62	57
Selling, general and administrative	33	33
Research and development	28	25
Other current assets	155		156
Accrued and other current liabilities	74		$ 80
Adempas \| Bayer AG \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	70	59
Adempas \| Other Intangible Assets \| Licenses and Other
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets	483
Verquvo \| Bayer AG \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	5	$ 7
Verquvo \| Other Intangible Assets \| Licenses and Other
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets	$ 49

Collaborative Arrangements - Ri

Collaborative Arrangements - Ridgeback Biotherapeutics LP (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	$ 15,775	$ 14,487
Cost of sales	3,540	3,926
Selling, general and administrative	2,483	2,479
Accrued and other current liabilities	14,102		$ 15,766
Ridgeback Biotherapeutics LP \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	191	221
Selling, general and administrative	16	27
Research and development expense (credit)	(5)	16
Accrued and other current liabilities	160		$ 113
Ridgeback Biotherapeutics LP \| Lagevrio \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	$ 350	$ 392

Collaborative Arrangements - Da

Collaborative Arrangements - Daiicho Sankyo - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)	Oct. 31, 2023 USD ($) candidate
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 3,992		$ 4,276
Daiichi Sankyo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of antibody drug conjugates obtained right and obligations \| candidate				3
Aggregate upfront payments due upon execution in collaborative arrangement				$ 4,000
Refundable upfront payments in collaborative arrangement				1,000
Maximum aggregate contingent milestone payments, per product, in collaborative arrangement				$ 5,500
Research and development	$ 69	$ 5,500	$ 0
Sales based royalty percentage				5%
Daiichi Sankyo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Ifinatamab Deruxtecan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Refundable upfront payments in collaborative arrangement				$ 500
Daiichi Sankyo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Patritumab Deruxtecan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Refundable upfront payments in collaborative arrangement				500
Aggregate upfront payments due upon lapse of time in collaborative arrangement				750
Daiichi Sankyo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Raludotatug Deruxtecan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate upfront payments due upon lapse of time in collaborative arrangement				$ 750
Liable contracted portion of research and development expenses to incur costs for in collaborative arrangement, percentage				75%
Liable contracted portion of research and development expenses to incur costs for in collaborative arrangement				$ 2,000
Daiichi Sankyo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Patritumab Deruxtecan And Raludotatug Deruxtecan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate upfront payments due upon lapse of time in collaborative arrangement		$ 1,500

Collaborative Arrangements - _4

Collaborative Arrangements - Daiicho Sankyo (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	$ 2,483		$ 2,479
Research and development	3,992		4,276
Accrued and other current liabilities	14,102	$ 15,766
Daiichi Sankyo \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	3		0
Research and development	69	5,500	$ 0
Accrued and other current liabilities	817	800
Other noncurrent liabilities	$ 750	$ 750

Collaborative Arrangements - Mo

Collaborative Arrangements - Moderna, Inc. - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 3,992	$ 4,276
Moderna, Inc. \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	69	$ 26
Prepaid Expense and Other Assets	$ 110

Collaborative Arrangements - _5

Collaborative Arrangements - Moderna, Inc. (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	$ 2,483	$ 2,479
Research and development	3,992	4,276
Accrued and other current liabilities	14,102		$ 15,766
Moderna, Inc. \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	2	1
Research and development	69	$ 26
Accrued and other current liabilities	$ 72		$ 63

Collaborative Arrangements - Br

Collaborative Arrangements - Bristol Meyers Squibb Company - Narrative (Details) - Bristol Myers Squibb Company - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Licensing Agreements
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty rate, deduction	0.50
Licensing Agreements \| Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent proceeds collaborative arrangement	$ 80
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative arrangement	$ 71	$ 43
Minimum \| Licensing Agreements
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty rate	20%
Maximum \| Licensing Agreements
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty rate	24%

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Restructuring - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2024	Mar. 31, 2023
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 246
Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Expected restructuring and related cost	$ 4,000
Estimate of cumulative pre tax costs that will be noncash	60%
Total pretax restructuring costs	$ 246
Cumulative costs since program inception	$ 436
Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		$ 97

Restructuring - Charges Activit

Restructuring - Charges Activities by Type of Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 246
Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	246
Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		$ 97
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	65
Accelerated Depreciation \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	65
Accelerated Depreciation \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		21
Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	92
Separation Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	92
Separation Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		41
Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	89
Other Exit Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	89
Other Exit Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		35
Cost of sales \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	116
Cost of sales \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		29
Cost of sales \| Accelerated Depreciation \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	65
Cost of sales \| Accelerated Depreciation \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		21
Cost of sales \| Separation Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0
Cost of sales \| Separation Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		0
Cost of sales \| Other Exit Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	51
Cost of sales \| Other Exit Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		8
Selling, general and administrative \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	5
Selling, general and administrative \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		1
Selling, general and administrative \| Accelerated Depreciation \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0
Selling, general and administrative \| Accelerated Depreciation \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		0
Selling, general and administrative \| Separation Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0
Selling, general and administrative \| Separation Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		0
Selling, general and administrative \| Other Exit Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	5
Selling, general and administrative \| Other Exit Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		1
Research and development \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	2
Research and development \| Accelerated Depreciation \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0
Research and development \| Separation Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0
Research and development \| Other Exit Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	2
Restructuring costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	123
Restructuring costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		67
Restructuring costs \| Accelerated Depreciation \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0
Restructuring costs \| Accelerated Depreciation \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		0
Restructuring costs \| Separation Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	92
Restructuring costs \| Separation Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		41
Restructuring costs \| Other Exit Costs \| Restructuring Program, 2024
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 31
Restructuring costs \| Other Exit Costs \| Restructuring Program, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs		$ 26

Restructuring - Activities by P

Restructuring - Activities by Program (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 712
Expenses	246
(Payments) receipts, net	(99)
Non-cash activity	(123)
Restructuring reserve, ending balance	736
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0
Expenses	65
(Payments) receipts, net	0
Non-cash activity	(65)
Restructuring reserve, ending balance	0
Separation Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	681
Expenses	92
(Payments) receipts, net	(67)
Non-cash activity	0
Restructuring reserve, ending balance	706
Other Exit Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	31
Expenses	89
(Payments) receipts, net	(32)
Non-cash activity	(58)
Restructuring reserve, ending balance	$ 30

Financial Instruments - Narrati

Financial Instruments - Narrative (Details) $ in Millions	3 Months Ended		12 Months Ended
Financial Instruments - Narrative (Details) $ in Millions	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Apr. 30, 2024 USD ($) interest_rate_swap
Derivative [Line Items]
Derivative, notional amount	$ 32,220		$ 30,551
Pretax net unrealized gain on derivatives maturing within the next 12 months estimated to be reclassified from AOCI to sales	113
Equity investments without readily determinable fair values	851	$ 942
Unrealized gains recognized on investments in equity securities without readily determinable fair value	4	1
Unrealized losses recognized on investments in equity securities without readily determinable fair values	5	21
Cumulative unrealized gains on investments	297
Cumulative unrealized losses on investments	69
Income from investments in equity securities, net	(143)	(450)
Fair value of loans payable and long-term debt, including current portion	30,400		32,000
Debt, carrying amount	34,200		35,100
Factored accounts receivable	2,700		3,000
Cash collateral received from counterparties	58		3
Equity Funds
Derivative [Line Items]
Equity securities held through ownership interest in investments funds	396	725
Income from investments in equity securities, net	2	$ (132)
Accounts Receivable Factoring Collections
Derivative [Line Items]
Restricted cash	$ 43		44
Senior Notes \| 4.50% Notes Due 2033
Derivative [Line Items]
Stated interest rate	4.50%
Level 2
Derivative [Line Items]
Cash equivalents	$ 4,600		6,000
Interest rate swap contracts \| Subsequent Event
Derivative [Line Items]
Number of interest rate swaps \| interest_rate_swap				2
Interest rate swap contracts \| 4.50% note due 2033
Derivative [Line Items]
Derivative, notional amount	1,000
Interest rate swap contracts \| 4.50% note due 2033 \| Subsequent Event
Derivative [Line Items]
Derivative, notional amount				$ 250
Derivatives Designated as Hedging Instruments
Derivative [Line Items]
Derivative, notional amount	13,424		12,754
Derivatives Designated as Hedging Instruments \| Interest rate swap contracts
Derivative [Line Items]
Derivative, notional amount	1,000		1,000
Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Derivative, notional amount	$ 18,796		$ 17,797
Maximum \| Derivatives Designated as Hedging Instruments
Derivative [Line Items]
Maximum average period of maturities of contracts in years (less than)	2 years
Maximum \| Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Maximum average period of maturities of contracts in years (less than)	6 months

Financial Instruments - Effect

Financial Instruments - Effect of Net Investment Hedges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	$ (2)	$ 1
Foreign exchange contracts \| Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	0	1
Euro-denominated notes
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	(62)	52
Euro-denominated notes \| Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	$ 0	$ 0

Financial Instruments - Summary

Financial Instruments - Summary of Interest Rate Swaps Held (Details)	Mar. 31, 2024 USD ($) interest_rate_swap	Dec. 31, 2023 USD ($)
Derivative [Line Items]
U.S dollar notional amount	$ 32,220,000,000	$ 30,551,000,000
Senior Notes \| 4.50% Notes Due 2033
Derivative [Line Items]
Stated interest rate	4.50%
Interest rate swap contracts \| 4.50% note due 2033
Derivative [Line Items]
Par Value of Debt	$ 1,500,000,000
Number of Interest Rate Swaps Held \| interest_rate_swap	4
U.S dollar notional amount	$ 1,000,000,000

Financial Instruments - Amounts

Financial Instruments - Amounts Recorded on Balance Sheet Related to Fair Value Hedges (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Hedged Liability, Statement of Financial Position [Extensible Enumeration]	Long-Term Debt	Long-Term Debt
Carrying Amount of Hedged Liabilities	$ 1,026	$ 1,056
Cumulative Amount of Fair Value Hedging Adjustment Increase Included in the Carrying Amount	$ 26	$ 56

Financial Instruments - Fair Va

Financial Instruments - Fair Value of Derivatives Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 357	$ 342
Fair value of derivative, liability	167	239
U.S dollar notional amount	32,220	30,551
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	234	189
Fair value of derivative, liability	11	77
U.S dollar notional amount	13,424	12,754
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	123	153
Fair value of derivative, liability	156	162
U.S dollar notional amount	18,796	17,797
Interest rate swap contracts \| Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 27	$ 57
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
U.S dollar notional amount	$ 1,000	$ 1,000
Foreign exchange contracts \| Derivatives Designated as Hedging Instruments \| Other Assets
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 32	$ 26
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
U.S dollar notional amount	$ 2,062	$ 1,929
Foreign exchange contracts \| Derivatives Designated as Hedging Instruments \| Other current assets
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 175	$ 106
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets
U.S dollar notional amount	$ 9,082	$ 6,138
Foreign exchange contracts \| Derivatives Designated as Hedging Instruments \| Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, liability	$ 10	$ 76
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accrued and other current liabilities	Accrued and other current liabilities
U.S dollar notional amount	$ 1,076	$ 3,680
Foreign exchange contracts \| Derivatives Designated as Hedging Instruments \| Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, liability	$ 1	$ 1
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Noncurrent Liabilities	Other Noncurrent Liabilities
U.S dollar notional amount	$ 204	$ 7
Foreign exchange contracts \| Derivatives Not Designated as Hedging Instruments \| Other Assets
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 2	$ 0
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
U.S dollar notional amount	$ 43	$ 0
Foreign exchange contracts \| Derivatives Not Designated as Hedging Instruments \| Other current assets
Derivatives, Fair Value [Line Items]
Fair value of derivative, asset	$ 121	$ 153
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets
U.S dollar notional amount	$ 9,428	$ 9,693
Foreign exchange contracts \| Derivatives Not Designated as Hedging Instruments \| Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, liability	$ 154	$ 162
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accrued and other current liabilities	Accrued and other current liabilities
U.S dollar notional amount	$ 9,282	$ 8,104
Foreign exchange contracts \| Derivatives Not Designated as Hedging Instruments \| Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative, liability	$ 2	$ 0
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Noncurrent Liabilities	Other Noncurrent Liabilities
U.S dollar notional amount	$ 43	$ 0

Financial Instruments - Informa

Financial Instruments - Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts recognized in the consolidated balance sheet, asset	$ 357	$ 342
Gross amount subject to offset in master netting arrangements not offset in the condensed balance sheet, asset	(111)	(215)
Cash collateral received, asset	(58)	(3)
Net amounts, asset	188	124
Gross amounts recognized in the consolidated balance sheet, liability	167	239
Gross amount subject to offset in master netting arrangements not offset in the condensed balance sheet, liability	(111)	(215)
Cash collateral received, liability	0	0
Net amounts, liability	$ 56	$ 24

Financial Instruments - Locatio

Financial Instruments - Location and Amount of Pretax (Gains) Losses of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 15,775	$ 14,487
Other (income) expense, net	(33)	89
Other comprehensive income (loss)	$ (113)	$ (115)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other (income) expense, net	Other (income) expense, net
Interest rate swap contracts \| Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ (30)	$ 0
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	30	0
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI on derivatives	209	(66)
Increase in Sales as a result of AOCL reclassifications	(44)	(101)
Foreign exchange contracts \| Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative Instruments, Gain (Loss) [Line Items]
Sales	44	101
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI on derivatives	0	(1)
Amount of gain recognized in Other (income) expense, net on derivatives	$ 0	$ (1)

Financial Instruments - Income

Financial Instruments - Income Statement Effects on Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Currency Swap \| Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 65	$ 13
Foreign Exchange Future \| Sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ (10)	$ 2

Financial Instruments - Infor_2

Financial Instruments - Information on Available-for-sale Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	$ 117		$ 337
Debt securities, unrealized gains	0		0
Debt securities, unrealized losses	0		0
Debt securities, fair value	117		337
Publicly traded equity securities, fair value	908		764
Total debt and publicly traded equity securities, fair value	1,025		1,101
Unrealized net gains (losses)	143	$ 338
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	40		252
Debt securities, unrealized gains	0		0
Debt securities, unrealized losses	0		0
Debt securities, fair value	40		252
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	77		72
Debt securities, unrealized gains	0		0
Debt securities, unrealized losses	0		0
Debt securities, fair value	77		72
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0		13
Debt securities, unrealized gains	0		0
Debt securities, unrealized losses	0		0
Debt securities, fair value	$ 0		$ 13

Financial Instruments - Financi

Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Assets
Investments	$ 117	$ 337
Publicly traded equity securities	908	764
Other Assets	12,326	11,996
Fair value of derivative, asset	357	342
Liabilities
Contingent consideration	226	354	$ 353	$ 456
Fair value of derivative, liability	167	239
Commercial paper
Assets
Investments	40	252
U.S. government and agency securities
Assets
Investments	77	72
Corporate notes and bonds
Assets
Investments	0	13
Fair Value, Measurements, Recurring
Assets
Investments	320	504
Other Assets	705	597
Fair value of derivative, asset	357	342
Total assets	1,382	1,443
Liabilities
Contingent consideration	226	354
Fair value of derivative, liability	167	239
Total liabilities	393	593
Fair Value, Measurements, Recurring \| Foreign exchange contracts
Assets
Fair value of derivative, asset	204	202
Liabilities
Fair value of derivative, liability	149	239
Fair Value, Measurements, Recurring \| Currency options
Assets
Fair value of derivative, asset	126	83
Liabilities
Fair value of derivative, liability	18	0
Fair Value, Measurements, Recurring \| Interest rate swap contracts
Assets
Fair value of derivative, asset	27	57
Fair Value, Measurements, Recurring \| Level 1
Assets
Investments	280	252
Other Assets	705	597
Fair value of derivative, asset	0	0
Total assets	985	849
Liabilities
Contingent consideration	0	0
Fair value of derivative, liability	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Foreign exchange contracts
Assets
Fair value of derivative, asset	0	0
Liabilities
Fair value of derivative, liability	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Currency options
Assets
Fair value of derivative, asset	0	0
Liabilities
Fair value of derivative, liability	0	0
Fair Value, Measurements, Recurring \| Level 1 \| Interest rate swap contracts
Assets
Fair value of derivative, asset	0	0
Fair Value, Measurements, Recurring \| Level 2
Assets
Investments	40	252
Other Assets	0	0
Fair value of derivative, asset	357	342
Total assets	397	594
Liabilities
Contingent consideration	0	0
Fair value of derivative, liability	167	239
Total liabilities	167	239
Fair Value, Measurements, Recurring \| Level 2 \| Foreign exchange contracts
Assets
Fair value of derivative, asset	204	202
Liabilities
Fair value of derivative, liability	149	239
Fair Value, Measurements, Recurring \| Level 2 \| Currency options
Assets
Fair value of derivative, asset	126	83
Liabilities
Fair value of derivative, liability	18	0
Fair Value, Measurements, Recurring \| Level 2 \| Interest rate swap contracts
Assets
Fair value of derivative, asset	27	57
Fair Value, Measurements, Recurring \| Level 3
Assets
Investments	0	0
Other Assets	0	0
Fair value of derivative, asset	0	0
Total assets	0	0
Liabilities
Contingent consideration	226	354
Fair value of derivative, liability	0	0
Total liabilities	226	354
Fair Value, Measurements, Recurring \| Level 3 \| Foreign exchange contracts
Assets
Fair value of derivative, asset	0	0
Liabilities
Fair value of derivative, liability	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Currency options
Assets
Fair value of derivative, asset	0	0
Liabilities
Fair value of derivative, liability	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Interest rate swap contracts
Assets
Fair value of derivative, asset	0	0
Fair Value, Measurements, Recurring \| Commercial paper
Assets
Investments	40	252
Fair Value, Measurements, Recurring \| Commercial paper \| Level 1
Assets
Investments	0	0
Fair Value, Measurements, Recurring \| Commercial paper \| Level 2
Assets
Investments	40	252
Fair Value, Measurements, Recurring \| Commercial paper \| Level 3
Assets
Investments	0	0
Fair Value, Measurements, Recurring \| U.S. government and agency securities
Assets
Debt securities, available-for-sale, noncurrent	77	72
Fair Value, Measurements, Recurring \| U.S. government and agency securities \| Level 1
Assets
Debt securities, available-for-sale, noncurrent	77	72
Fair Value, Measurements, Recurring \| U.S. government and agency securities \| Level 2
Assets
Debt securities, available-for-sale, noncurrent	0	0
Fair Value, Measurements, Recurring \| U.S. government and agency securities \| Level 3
Assets
Debt securities, available-for-sale, noncurrent	0	0
Fair Value, Measurements, Recurring \| Corporate notes and bonds
Assets
Debt securities, available-for-sale, noncurrent	0	13
Fair Value, Measurements, Recurring \| Corporate notes and bonds \| Level 1
Assets
Debt securities, available-for-sale, noncurrent	0	13
Fair Value, Measurements, Recurring \| Corporate notes and bonds \| Level 2
Assets
Debt securities, available-for-sale, noncurrent	0	0
Fair Value, Measurements, Recurring \| Corporate notes and bonds \| Level 3
Assets
Debt securities, available-for-sale, noncurrent	0	0
Fair Value, Measurements, Recurring \| Publicly traded equity securities
Assets
Publicly traded equity securities	280	252
Publicly traded equity securities	628	512
Fair Value, Measurements, Recurring \| Publicly traded equity securities \| Level 1
Assets
Publicly traded equity securities	280	252
Publicly traded equity securities	628	512
Liabilities
Securities, fair value, which are subject to a contractual sale restriction	266
Fair Value, Measurements, Recurring \| Publicly traded equity securities \| Level 2
Assets
Publicly traded equity securities	0	0
Publicly traded equity securities	0	0
Fair Value, Measurements, Recurring \| Publicly traded equity securities \| Level 3
Assets
Publicly traded equity securities	0	0
Publicly traded equity securities	$ 0	$ 0

Financial Instruments - Infor_3

Financial Instruments - Information About Changes in Liabilities for Contingent Consideration (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 354	$ 456
Changes in estimated fair value	(2)	14
Payments	(126)	(117)
Fair value, ending balance	226	$ 353
Sanofi Pasteur
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Current liability	$ 133
Contingent consideration, measurement input, discount rate	0.115

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Finished goods	$ 1,902	$ 1,954
Raw materials and work in process	8,366	8,037
Supplies	276	277
Total	10,544	10,268
Decrease to LIFO cost	(621)	(562)
Total current and noncurrent inventories	9,923	9,706
Recognized as:
Inventories	6,510	6,358
Other Assets	$ 3,413	$ 3,348

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Inventory [Line Items]
Inventories classified in Other assets	$ 3,413	$ 3,348
Inventories Not Expected to be Sold Within One Year
Inventory [Line Items]
Inventories classified in Other assets	2,600	2,600
Inventories Produced in Preparation for Product Launches
Inventory [Line Items]
Inventories classified in Other assets	$ 861	$ 790

Contingencies (Details)

Contingencies (Details) $ in Millions			3 Months Ended
Contingencies (Details) $ in Millions	Apr. 13, 2023 patent	Dec. 19, 2022	Mar. 31, 2024 USD ($) case employee company	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Jul. 27, 2023 motion_for_summary_judgment
Pending Litigation \| Commercial and Other Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims			2
Loss contingency, number of plaintiffs \| employee			2
Loss contingency, number of motion for summary judgments \| motion_for_summary_judgment						2
Legal Defense Costs
Loss Contingencies [Line Items]
Legal defense costs reserve \| $			$ 220		$ 210
Zetia antitrust litigation
Loss Contingencies [Line Items]
Loss related to litigation settlement \| $				$ 572.5
Gardasil/Gardasil 9 \| Pending Litigation \| U.S.
Loss Contingencies [Line Items]
Loss contingency, pending claims			190
Gardasil/Gardasil 9 \| Pending Litigation \| Non-US
Loss Contingencies [Line Items]
Loss contingency, pending claims			15
Bridion \| Patents
Loss Contingencies [Line Items]
Loss contingency, claims settled \| company			5
Bridion \| Patents \| Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims \| company			2
Loss contingency, trial period		1 day
Keytruda \| Patents \| Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, number of patents allegedly infringed \| patent	9
Dr. Scholl's \| Pending Litigation \| U.S.
Loss Contingencies [Line Items]
Loss contingency, pending claims			275
Januvia/Janumet
Loss Contingencies [Line Items]
Loss contingency, claims settled			26

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, beginning balance (in shares)	3,577,103,522
Treasury stock, beginning balance (in shares)	1,045,470,249
Equity, beginning balance	$ 37,635	$ 46,058
Net (loss) income attributable to Merck & Co., Inc.	4,762	2,821
Other comprehensive income (loss), net of taxes	(113)	(115)
Cash dividends declared on common stock	(1,960)	(1,863)
Treasury stock shares purchased	(122)	(149)
Share-based compensation plans and other	217	149
Net income attributable to noncontrolling interests	$ 5	4
Common stock, ending balance (in shares)	3,577,103,522
Treasury stock, ending balance (in shares)	1,044,402,655
Equity, ending balance	$ 40,424	$ 46,905
Cash dividends declared on common stock (in dollars per share)	$ 0.77	$ 0.73
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, beginning balance (in shares)	3,577,000,000	3,577,000,000
Equity, beginning balance	$ 1,788	$ 1,788
Common stock, ending balance (in shares)	3,577,000,000	3,577,000,000
Equity, ending balance	$ 1,788	$ 1,788
Other Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	44,509	44,379
Share-based compensation plans and other	89	88
Equity, ending balance	44,598	44,467
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	53,895	61,081
Net (loss) income attributable to Merck & Co., Inc.	4,762	2,821
Cash dividends declared on common stock	(1,960)	(1,863)
Equity, ending balance	56,697	62,039
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	(5,161)	(4,768)
Other comprehensive income (loss), net of taxes	(113)	(115)
Equity, ending balance	$ (5,274)	$ (4,883)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock, beginning balance (in shares)	1,045,000,000	1,039,000,000
Equity, beginning balance	$ (57,450)	$ (56,489)
Treasury stock shares purchased (in shares)	1,000,000	1,000,000
Treasury stock shares purchased	$ (122)	$ (149)
Share-based compensation plans and other (in shares)	(2,000,000)	0
Share-based compensation plans and other	$ 127	$ 61
Treasury stock, ending balance (in shares)	1,044,000,000	1,040,000,000
Equity, ending balance	$ (57,445)	$ (56,577)
Non- controlling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	54	67
Share-based compensation plans and other	1
Net income attributable to noncontrolling interests	5	4
Equity, ending balance	$ 60	$ 71

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Plans - Net Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 8
Interest cost	14	16
Expected return on plan assets	(20)	(16)
Amortization of unrecognized prior service credit	(11)	(12)
Net loss (gain) amortization	(12)	(11)
Net periodic benefit cost	(21)	(15)
U.S. \| Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	86	76
Interest cost	134	133
Expected return on plan assets	(207)	(187)
Amortization of unrecognized prior service credit	0	0
Net loss (gain) amortization	10	0
Termination benefits	3	0
Curtailments	0	2
Settlements	0	21
Net periodic benefit cost	26	45
International \| Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	61	49
Interest cost	74	74
Expected return on plan assets	(139)	(128)
Amortization of unrecognized prior service credit	(3)	(3)
Net loss (gain) amortization	1	(1)
Termination benefits	0	0
Curtailments	0	0
Settlements	0	0
Net periodic benefit cost	$ (6)	$ (9)

Pension and Other Postretirem_4

Pension and Other Postretirement Benefit Plans - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Retirement Benefits [Abstract]
Partial settlement charge	$ 21
Increase to pension liabilities due to remeasurement	$ 44

Other (Income) Expense, Net - S

Other (Income) Expense, Net - Schedule of Other (Income) Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Other Income and Expenses [Abstract]
Interest income	$ (73)	$ (112)
Interest expense	303	242
Exchange losses	83	61
Income from investments in equity securities, net	(143)	(450)
Net periodic defined benefit plan (credit) cost other than service cost	(160)	(115)
Other, net	(43)	463
Other (income) expense, net	$ (33)	$ 89

Other (Income) Expense, Net - N

Other (Income) Expense, Net - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Loss Contingencies [Line Items]
Interest Paid	$ 217	$ 208
Zetia antitrust litigation
Loss Contingencies [Line Items]
Loss related to litigation settlement		$ 572.5

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended
Income Taxes (Details) - USD ($)	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Effective income tax rate	15.90%	22.60%
Unfavorable discrete impact on tax rate	1.60%	5.50%
Tax benefit resulting from acquisition charge	$ 0	$ 0

Earnings Per Share - Calculatio

Earnings Per Share - Calculations of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net Income Attributable to Merck & Co., Inc., basic	$ 4,762	$ 2,821
Net Income Attributable to Merck & Co., Inc., diluted	$ 4,762	$ 2,821
Average common shares outstanding (in shares)	2,533	2,538
Common shares issuable (in shares)	11	13
Average common shares outstanding assuming dilution (in shares)	2,544	2,551
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.88	$ 1.11
Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.87	$ 1.11

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Antidilutive shares (in shares)	3	1

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	$ 37,635	$ 46,058
Other comprehensive income (loss), net of taxes	(113)	(115)
Equity, ending balance	40,424	46,905
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(24)	73
Other comprehensive income (loss) before reclassification adjustments, pretax	209	(66)
Tax	(44)	14
Other comprehensive income (loss) before reclassification adjustments, net of taxes	165	(52)
Reclassification adjustments, pretax	(44)	(102)
Tax	9	21
Reclassification adjustments, net of taxes	(35)	(81)
Other comprehensive income (loss), net of taxes	130	(133)
Equity, ending balance	106	(60)
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(2,793)	(2,408)
Other comprehensive income (loss) before reclassification adjustments, pretax	5	(47)
Tax	(4)	2
Other comprehensive income (loss) before reclassification adjustments, net of taxes	1	(45)
Reclassification adjustments, pretax	(15)	(7)
Tax	9	2
Reclassification adjustments, net of taxes	(6)	(5)
Other comprehensive income (loss), net of taxes	(5)	(50)
Equity, ending balance	(2,798)	(2,458)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(2,344)	(2,433)
Other comprehensive income (loss) before reclassification adjustments, pretax	(225)	79
Tax	(13)	(20)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(238)	59
Reclassification adjustments, pretax	0	9
Tax	0	0
Reclassification adjustments, net of taxes	0	9
Other comprehensive income (loss), net of taxes	(238)	68
Equity, ending balance	(2,582)	(2,365)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(5,161)	(4,768)
Other comprehensive income (loss) before reclassification adjustments, pretax	(11)	(34)
Tax	(61)	(4)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(72)	(38)
Reclassification adjustments, pretax	(59)	(100)
Tax	18	23
Reclassification adjustments, net of taxes	(41)	(77)
Other comprehensive income (loss), net of taxes	(113)	(115)
Equity, ending balance	$ (5,274)	$ (4,883)

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details) $ in Billions	3 Months Ended
Segment Reporting - Narrative (Details) $ in Billions	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)
Segment Reporting [Abstract]
Number of operating segments \| segment	2
Sales discounts \| $	$ 3.2	$ 3.1

Segment Reporting - Sales from

Segment Reporting - Sales from Products (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Sales	$ 15,775	$ 14,487
Increase in hedge revenue	54	99
Revenue related to the sale of the marketing rights	61	51
U.S.
Segment Reporting Information [Line Items]
Sales	7,478	6,659
Int’l
Segment Reporting Information [Line Items]
Sales	8,297	7,828
Operating Segments
Segment Reporting Information [Line Items]
Sales	15,517	14,212
Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	7,410	6,599
Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	8,107	7,614
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	258	275
Corporate, Non-Segment \| U.S.
Segment Reporting Information [Line Items]
Sales	68	60
Corporate, Non-Segment \| Int’l
Segment Reporting Information [Line Items]
Sales	190	214
Pharmaceutical \| Operating Segments
Segment Reporting Information [Line Items]
Sales	14,006	12,721
Pharmaceutical \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	6,936	6,117
Pharmaceutical \| Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	7,070	6,604
Pharmaceutical \| Operating Segments \| Keytruda
Segment Reporting Information [Line Items]
Sales	6,947	5,795
Pharmaceutical \| Operating Segments \| Keytruda \| U.S.
Segment Reporting Information [Line Items]
Sales	4,119	3,485
Pharmaceutical \| Operating Segments \| Keytruda \| Int’l
Segment Reporting Information [Line Items]
Sales	2,828	2,310
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	292	275
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| U.S.
Segment Reporting Information [Line Items]
Sales	135	142
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| Int’l
Segment Reporting Information [Line Items]
Sales	157	133
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	255	232
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| U.S.
Segment Reporting Information [Line Items]
Sales	173	153
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| Int’l
Segment Reporting Information [Line Items]
Sales	82	79
Pharmaceutical \| Operating Segments \| Welireg
Segment Reporting Information [Line Items]
Sales	85	42
Pharmaceutical \| Operating Segments \| Welireg \| U.S.
Segment Reporting Information [Line Items]
Sales	77	41
Pharmaceutical \| Operating Segments \| Welireg \| Int’l
Segment Reporting Information [Line Items]
Sales	7	1
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl
Segment Reporting Information [Line Items]
Sales	71	43
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| U.S.
Segment Reporting Information [Line Items]
Sales	58	30
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| Int’l
Segment Reporting Information [Line Items]
Sales	12	12
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	2,249	1,972
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| U.S.
Segment Reporting Information [Line Items]
Sales	488	416
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| Int’l
Segment Reporting Information [Line Items]
Sales	1,761	1,556
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	570	528
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| U.S.
Segment Reporting Information [Line Items]
Sales	438	421
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| Int’l
Segment Reporting Information [Line Items]
Sales	133	107
Pharmaceutical \| Operating Segments \| Vaxneuvance
Segment Reporting Information [Line Items]
Sales	219	106
Pharmaceutical \| Operating Segments \| Vaxneuvance \| U.S.
Segment Reporting Information [Line Items]
Sales	161	94
Pharmaceutical \| Operating Segments \| Vaxneuvance \| Int’l
Segment Reporting Information [Line Items]
Sales	58	13
Pharmaceutical \| Operating Segments \| RotaTeq
Segment Reporting Information [Line Items]
Sales	216	297
Pharmaceutical \| Operating Segments \| RotaTeq \| U.S.
Segment Reporting Information [Line Items]
Sales	149	180
Pharmaceutical \| Operating Segments \| RotaTeq \| Int’l
Segment Reporting Information [Line Items]
Sales	67	117
Pharmaceutical \| Operating Segments \| Pneumovax 23
Segment Reporting Information [Line Items]
Sales	61	96
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| U.S.
Segment Reporting Information [Line Items]
Sales	6	40
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| Int’l
Segment Reporting Information [Line Items]
Sales	55	56
Pharmaceutical \| Operating Segments \| Bridion
Segment Reporting Information [Line Items]
Sales	440	487
Pharmaceutical \| Operating Segments \| Bridion \| U.S.
Segment Reporting Information [Line Items]
Sales	329	276
Pharmaceutical \| Operating Segments \| Bridion \| Int’l
Segment Reporting Information [Line Items]
Sales	111	210
Pharmaceutical \| Operating Segments \| Prevymis
Segment Reporting Information [Line Items]
Sales	174	129
Pharmaceutical \| Operating Segments \| Prevymis \| U.S.
Segment Reporting Information [Line Items]
Sales	74	54
Pharmaceutical \| Operating Segments \| Prevymis \| Int’l
Segment Reporting Information [Line Items]
Sales	100	75
Pharmaceutical \| Operating Segments \| Dificid
Segment Reporting Information [Line Items]
Sales	73	65
Pharmaceutical \| Operating Segments \| Dificid \| U.S.
Segment Reporting Information [Line Items]
Sales	68	62
Pharmaceutical \| Operating Segments \| Dificid \| Int’l
Segment Reporting Information [Line Items]
Sales	5	3
Pharmaceutical \| Operating Segments \| Zerbaxa
Segment Reporting Information [Line Items]
Sales	56	50
Pharmaceutical \| Operating Segments \| Zerbaxa \| U.S.
Segment Reporting Information [Line Items]
Sales	33	27
Pharmaceutical \| Operating Segments \| Zerbaxa \| Int’l
Segment Reporting Information [Line Items]
Sales	23	23
Pharmaceutical \| Operating Segments \| Noxafil
Segment Reporting Information [Line Items]
Sales	56	60
Pharmaceutical \| Operating Segments \| Noxafil \| U.S.
Segment Reporting Information [Line Items]
Sales	8	14
Pharmaceutical \| Operating Segments \| Noxafil \| Int’l
Segment Reporting Information [Line Items]
Sales	48	46
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo
Segment Reporting Information [Line Items]
Sales	98	99
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| U.S.
Segment Reporting Information [Line Items]
Sales	90	83
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| Int’l
Segment Reporting Information [Line Items]
Sales	8	16
Pharmaceutical \| Operating Segments \| Adempas
Segment Reporting Information [Line Items]
Sales	70	59
Pharmaceutical \| Operating Segments \| Adempas \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0
Pharmaceutical \| Operating Segments \| Adempas \| Int’l
Segment Reporting Information [Line Items]
Sales	70	59
Pharmaceutical \| Operating Segments \| Lagevrio
Segment Reporting Information [Line Items]
Sales	350	392
Pharmaceutical \| Operating Segments \| Lagevrio \| U.S.
Segment Reporting Information [Line Items]
Sales	45	(2)
Pharmaceutical \| Operating Segments \| Lagevrio \| Int’l
Segment Reporting Information [Line Items]
Sales	305	394
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	111	123
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| U.S.
Segment Reporting Information [Line Items]
Sales	50	52
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| Int’l
Segment Reporting Information [Line Items]
Sales	61	71
Pharmaceutical \| Operating Segments \| Delstrigo
Segment Reporting Information [Line Items]
Sales	56	44
Pharmaceutical \| Operating Segments \| Delstrigo \| U.S.
Segment Reporting Information [Line Items]
Sales	12	11
Pharmaceutical \| Operating Segments \| Delstrigo \| Int’l
Segment Reporting Information [Line Items]
Sales	44	33
Pharmaceutical \| Operating Segments \| Pifeltro
Segment Reporting Information [Line Items]
Sales	42	34
Pharmaceutical \| Operating Segments \| Pifeltro \| U.S.
Segment Reporting Information [Line Items]
Sales	29	24
Pharmaceutical \| Operating Segments \| Pifeltro \| Int’l
Segment Reporting Information [Line Items]
Sales	13	10
Pharmaceutical \| Operating Segments \| Belsomra
Segment Reporting Information [Line Items]
Sales	46	56
Pharmaceutical \| Operating Segments \| Belsomra \| U.S.
Segment Reporting Information [Line Items]
Sales	15	16
Pharmaceutical \| Operating Segments \| Belsomra \| Int’l
Segment Reporting Information [Line Items]
Sales	32	40
Pharmaceutical \| Operating Segments \| Simponi
Segment Reporting Information [Line Items]
Sales	184	180
Pharmaceutical \| Operating Segments \| Simponi \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0
Pharmaceutical \| Operating Segments \| Simponi \| Int’l
Segment Reporting Information [Line Items]
Sales	184	180
Pharmaceutical \| Operating Segments \| Remicade
Segment Reporting Information [Line Items]
Sales	39	51
Pharmaceutical \| Operating Segments \| Remicade \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0
Pharmaceutical \| Operating Segments \| Remicade \| Int’l
Segment Reporting Information [Line Items]
Sales	39	51
Pharmaceutical \| Operating Segments \| Januvia
Segment Reporting Information [Line Items]
Sales	419	551
Pharmaceutical \| Operating Segments \| Januvia \| U.S.
Segment Reporting Information [Line Items]
Sales	183	271
Pharmaceutical \| Operating Segments \| Januvia \| Int’l
Segment Reporting Information [Line Items]
Sales	236	280
Pharmaceutical \| Operating Segments \| Janumet
Segment Reporting Information [Line Items]
Sales	251	329
Pharmaceutical \| Operating Segments \| Janumet \| U.S.
Segment Reporting Information [Line Items]
Sales	39	56
Pharmaceutical \| Operating Segments \| Janumet \| Int’l
Segment Reporting Information [Line Items]
Sales	212	272
Pharmaceutical \| Operating Segments \| Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	576	626
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| U.S.
Segment Reporting Information [Line Items]
Sales	157	171
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| Int’l
Segment Reporting Information [Line Items]
Sales	419	457
Animal Health \| Operating Segments
Segment Reporting Information [Line Items]
Sales	1,511	1,491
Animal Health \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	474	482
Animal Health \| Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	1,037	1,010
Animal Health \| Operating Segments \| Livestock
Segment Reporting Information [Line Items]
Sales	850	849
Animal Health \| Operating Segments \| Livestock \| U.S.
Segment Reporting Information [Line Items]
Sales	166	174
Animal Health \| Operating Segments \| Livestock \| Int’l
Segment Reporting Information [Line Items]
Sales	683	676
Animal Health \| Operating Segments \| Companion Animal
Segment Reporting Information [Line Items]
Sales	661	642
Animal Health \| Operating Segments \| Companion Animal \| U.S.
Segment Reporting Information [Line Items]
Sales	308	308
Animal Health \| Operating Segments \| Companion Animal \| Int’l
Segment Reporting Information [Line Items]
Sales	$ 354	$ 334

Segment Reporting - Consolidate

Segment Reporting - Consolidated Sales by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenue from External Customer [Line Items]
Sales	$ 15,775	$ 14,487
United States
Revenue from External Customer [Line Items]
Sales	7,478	6,659
Europe, Middle East and Africa
Revenue from External Customer [Line Items]
Sales	3,563	3,303
China
Revenue from External Customer [Line Items]
Sales	1,772	1,715
Japan
Revenue from External Customer [Line Items]
Sales	821	758
Latin America
Revenue from External Customer [Line Items]
Sales	796	661
Asia Pacific (other than China and Japan)
Revenue from External Customer [Line Items]
Sales	724	846
Other
Revenue from External Customer [Line Items]
Sales	$ 621	$ 545

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Segment Profits to Income before Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Profits	$ 5,670	$ 3,650
Interest income	73	112
Interest expense	(303)	(242)
Amortization	(473)	(543)
Depreciation	(511)	(448)
Research and development	(3,992)	(4,276)
Restructuring costs	(123)	(67)
Operating Segments
Segment Reporting Information [Line Items]
Profits	11,459	9,706
Operating Segments \| Pharmaceutical segment
Segment Reporting Information [Line Items]
Profits	10,904	9,140
Operating Segments \| Animal Health segment
Segment Reporting Information [Line Items]
Profits	555	566
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Profits	146	164
Segment Reconciling Items
Segment Reporting Information [Line Items]
Interest income	73	112
Interest expense	(303)	(242)
Amortization	(473)	(543)
Depreciation	(452)	(398)
Research and development	(3,851)	(4,147)
Restructuring costs	(123)	(67)
Charge for Zetia antitrust litigation settlements	0	(573)
Other unallocated, net	$ (806)	$ (362)