Mallinckrodt (MNKTQ) 8-KMallinckrodt plc Reports First Quarter 2024 Financial Results and Reaffirms Full Year Guidance

Exhibit 99.1

Mallinckrodt plc Reports First Quarter 2024 Financial Results and Reaffirms Full Year Guidance

Mr. Olafsson continued, “I am proud of our teams and the progress we have made together. We have positive momentum across the business, and I am confident in our path forward as we build on our strengths to continue driving growth and innovation for our patients.”

Mallinckrodt’s net sales in the first quarter of 2024 were $467.8 million, as compared to $424.6 million in the first quarter of 2023. This reflects an increase of 10.2% on a reported and constant currency basis.

The Company’s Specialty Brands segment reported net sales of $257.3 million, as compared to $252.0 million in the first quarter of 2023. This reflects an increase of 2.1% on a reported basis and 2.0% on a constant currency basis, primarily due to continued demand stabilization for Acthar Gel and the launch of Terlivaz, partially offset by the impact of competition.

Mallinckrodt’s Specialty Generics segment reported net sales of $210.5 million, as compared to $172.6 million in the first quarter of 2023. This reflects an increase of 22.0% on a reported and constant currency basis, primarily due to growth in finished-dosage products as the broader market experienced ongoing disruptions in product quality and supply and strong performance in the Acetaminophen (APAP) business.

The Company’s net loss for the first quarter of 2024 was $65.4 million, as compared to a net loss of $249.3 million in the first quarter of 2023, an improvement of 73.8%.

Mallinckrodt’s Adjusted EBITDA in the first quarter of 2024 was $144.9 million, as compared to $123.5 million in the first quarter of 2023, an increase of 17.3%. This increase was primarily due to strength in the Specialty Generics segment,

growth in Acthar Gel and the launch of Terlivaz, partially offset by the impact of competition. In addition, the Company continues to invest in the launch of Terlivaz and expects to incur incremental cash compensation costs in lieu of stock compensation, which is expected to impact Adjusted EBITDA moving forward.

Adjusted gross profit as a percentage of sales was 64.0% for the first quarter of 2024, as compared to 62.0% for the first quarter of 2023. The increase in adjusted gross profit was primarily due to the Company’s shift in overall product mix.

Mallinckrodt's cash balance at the end of the first quarter of 2024 was $253.6 million. Total principal debt outstanding at the end of the first quarter of 2024 was $1,645.7 million, with net debt of $1,392.1 million outstanding.

Please see “Non-GAAP Financial Measures” included in this release for a discussion of non-GAAP measures and reconciliation of GAAP and non-GAAP financial measures for the first quarter.

Please see the “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” sections of the Company’s Quarterly Report on Form 10-Q for the quarter ended March 29, 2024 to be filed with the Securities and Exchange Commission for additional information.

The Company does not provide a reconciliation of forward-looking non-GAAP guidance to the comparable GAAP measures as these items are inherently uncertain and difficult to estimate and cannot be predicted without unreasonable effort.

Mallinckrodt uses its website as a channel of distribution of important company information, such as press releases, investor presentations and other financial information. It also uses its website to expedite public access to time-critical information regarding the Company in advance of or in lieu of distributing a press release or a filing with the U.S. Securities and Exchange Commission (“SEC”) disclosing the same information. Therefore, investors should look to the Investor Relations page of the website for important and time-critical information. Visitors to the website can also register to receive automatic e-mail and other notifications alerting them when new information is made available on the Investor Relations page of the website.

This press release contains financial measures, including Adjusted EBITDA, adjusted gross profit, adjusted SG&A expenses, adjusted R&D expenses, net sales growth (loss) on a constant-currency basis, and net debt, which are considered "non-GAAP" financial measures under applicable SEC rules and regulations.

Adjusted EBITDA represents net income or loss prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) and adjusted for certain items that management believes are not reflective of the operational performance of the business. Adjustments to GAAP amounts include, as applicable to each measure, interest expense, net; income taxes; depreciation; amortization; restructuring charges, net; non-restructuring impairment charges; inventory step-up expense; discontinued operations; changes in fair value of contingent consideration obligations; significant legal and environmental charges; divestitures; liabilities management and separation costs; gains on debt extinguishment, net; unrealized gain or loss on equity investment; reorganization items, net; share-based compensation; fresh-start inventory related expenses; and other items identified by the Company.

Adjusted gross profit, adjusted SG&A expenses and adjusted R&D expenses represent amounts prepared in accordance with GAAP, adjusted for certain items that management believes are not reflective of the operational performance of the business. Adjustments to GAAP amounts include, as applicable to each measure, the aforementioned items in the Adjusted EBITDA paragraph. The adjustments for these items are on a pre-tax basis for adjusted gross profit and adjusted SG&A expenses.

Segment net sales growth (loss) on a constant-currency basis measures the change in segment net sales between current- and prior-year periods using a constant currency, the exchange rate in effect during the applicable prior-year period.

Net debt of $1,392.1 million as of March 29, 2024, reflects $1,645.7 million in total debt outstanding on a GAAP basis less $253.6 million in cash and cash equivalents (unrestricted cash) on a GAAP basis.

The Company has provided these adjusted financial measures because they are used by management, along with financial measures in accordance with GAAP, to evaluate the Company's operating performance and liquidity. In addition, the Company believes that they will be used by investors to measure Mallinckrodt's operating results. Management believes that presenting these adjusted measures provides useful information about the Company's performance across reporting periods on a consistent basis by excluding items that the Company does not believe are indicative of its core operating performance.

These adjusted measures should be considered supplemental to and not a substitute for financial information prepared in accordance with GAAP. The Company's definition of these adjusted measures may differ from similarly titled measures used by others.

Because adjusted financial measures exclude the effect of items that will increase or decrease the Company's reported results of operations, management strongly encourages investors to review the Company's unaudited condensed consolidated financial statements and publicly filed reports in their entirety. A reconciliation of certain of these historical adjusted financial measures to the most directly comparable GAAP financial measures is included in the tables accompanying this release.

Further information regarding non-GAAP financial measures can be found on the Investor Relations page of the Company's website.

Mallinckrodt’s financial results presented in this press release include Successor and Predecessor periods. The Successor period runs for the three months ended March 29, 2024, while the Predecessor period is for the three months ended March 31, 2023. We do not believe that reviewing the results of the Successor period in isolation would be useful in identifying trends in or reaching conclusions regarding our overall operating performance. Management believes that our key performance metrics such as net sales and segment results of operations for the three months ended March 29, 2024 (Successor) provide a meaningful comparison and are useful in identifying current business trends when compared to the three months ended March 31, 2023 (Predecessor).

Mallinckrodt’s results of operations as reported in its unaudited condensed consolidated financial statements for the Successor and Predecessor periods are in accordance with GAAP. The comparison of the Predecessor and Successor periods for the periods presented here is not in accordance with GAAP. However, the Company believes that the comparison is useful for management and investors to assess Mallinckrodt’s ongoing financial and operational performance and trends.

Statements in this press release that are not strictly historical, including statements regarding future financial condition and operating results, expected product launches, legal, economic, business, competitive and/or regulatory factors affecting Mallinckrodt’s businesses, the ongoing strategic review, and any other statements regarding events or developments Mallinckrodt believes or anticipates will or may occur in the future, may be “forward-looking” statements within the meaning of the Private Securities Litigation Reform Act of 1995, and involve a number of risks and uncertainties.

There are a number of important factors that could cause actual events to differ materially from those suggested or indicated by such forward-looking statements and you should not place undue reliance on any such forward-looking statements. These factors include risks and uncertainties related to, among other things: the comparability of Mallinckrodt’s post-emergence financial results and the projections filed with the Bankruptcy Court; the lack of comparability of Mallinckrodt’s historical financial statements and information contained in its financial statements after the adoption of fresh-start accounting following emergence from the 2023 bankruptcy proceedings; changes in Mallinckrodt’s board of directors, business strategy and performance; Mallinckrodt’s evaluation of the assets across its portfolio, and its related pursuit of any divestiture opportunities; the exercise of contingent value rights by the Opioid Master Disbursement Trust II (the “Trust”); Mallinckrodt’s repurchases of debt securities; the liquidity, results of operations and businesses of Mallinckrodt and its subsidiaries; governmental investigations and inquiries, regulatory actions, and lawsuits, in each case related to Mallinckrodt or its officers; Mallinckrodt’s contractual and court-ordered compliance obligations that, if violated, could result in penalties; historical commercialization of opioids, including compliance with and restrictions under the global settlement to resolve all opioid-related claims; matters related to Acthar Gel, including the settlement with governmental parties to resolve certain disputes and compliance with and restrictions under the related corporate integrity agreement; the ability to maintain relationships with Mallinckrodt’s suppliers, customers, employees and other third parties

following the emergence from the 2023 bankruptcy proceedings, as well as perceptions of the Company's increased performance and credit risks associated with its constrained liquidity position and capital structure, which reflects a recently increased risk of additional bankruptcy or insolvency proceedings; the possibility that Mallinckrodt may be unable to achieve its business and strategic goals even now that the emergence from the 2023 bankruptcy proceedings was successfully consummated; the non-dischargeability of certain claims against Mallinckrodt as part of the bankruptcy process; developing, funding and executing Mallinckrodt's business plan; scrutiny from governments, legislative bodies and enforcement agencies related to sales, marketing and pricing practices; pricing pressure on certain of Mallinckrodt’s products due to legal changes or changes in insurers’ or other payers’ reimbursement practices resulting from recent increased public scrutiny of healthcare and pharmaceutical costs; the reimbursement practices of governmental health administration authorities, private health coverage insurers and other third-party payers; complex reporting and payment obligations under the Medicare and Medicaid rebate programs and other governmental purchasing and rebate programs; cost containment efforts of customers, purchasing groups, third-party payers and governmental organizations; changes in or failure to comply with relevant laws and regulations; any undesirable side effects caused by Mallinckrodt’s approved and investigational products, which could limit their commercial profile or result in other negative consequences; Mallinckrodt’s and its partners’ ability to successfully develop, commercialize or launch new products or expand commercial opportunities of existing products, including Acthar Gel (repository corticotropin injection) Single-Dose Pre-filled SelfJect™ Injector and the INOmax Evolve platform; Mallinckrodt’s ability to successfully identify or discover additional products or product candidates; Mallinckrodt’s ability to navigate price fluctuations; competition; Mallinckrodt’s and its partners’ ability to protect intellectual property rights, including in relation to ongoing and future litigation; limited clinical trial data for Acthar Gel; the timing, expense and uncertainty associated with clinical studies and related regulatory processes; product liability losses and other litigation liability; material health, safety and environmental liabilities; business development activities or other strategic transactions; attraction and retention of key personnel; the effectiveness of information technology infrastructure, including risks of external attacks or failures; customer concentration; Mallinckrodt’s reliance on certain individual products that are material to its financial performance; Mallinckrodt’s ability to receive sufficient procurement and production quotas granted by the U.S. Drug Enforcement Administration; complex manufacturing processes; reliance on third-party manufacturers and supply chain providers and related market disruptions; conducting business internationally; Mallinckrodt’s ability to achieve expected benefits from prior or future restructuring activities; Mallinckrodt’s significant levels of intangible assets and related impairment testing; natural disasters or other catastrophic events; Mallinckrodt’s substantial indebtedness and settlement obligation, its ability to generate sufficient cash to reduce its indebtedness and its potential need and ability to incur further indebtedness; restrictions contained in the agreements governing Mallinckrodt’s indebtedness and settlement obligation on Mallinckrodt’s operations, future financings and use of proceeds; actions taken by third parties, including the Company's creditors, the Trust and other stakeholders; Mallinckrodt’s variable rate indebtedness; Mallinckrodt's tax treatment by the Internal Revenue Service under Section 7874 and Section 382 of the Internal Revenue Code of 1986, as amended; future changes to applicable tax laws or the impact of disputes with governmental tax authorities; the impact of Irish laws; and the impact of deregistration of Mallinckrodt’s ordinary shares.

The “Risk Factors” and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of Mallinckrodt’s Annual Report on Form 10-K for the fiscal year ended December 29, 2023 and Quarterly Report on Form 10-Q for the quarterly period ended March 29, 2024, to be filed with the SEC, and other filings with the SEC, all of which are on file with the SEC and available on Mallinckrodt's website at http://www.sec.gov and https://www.mallinckrodt.com, respectively, identify and describe in more detail the risks and uncertainties to which Mallinckrodt’s businesses are subject. There may be other risks and uncertainties that we are unable to predict at this time or that we currently do not expect to have a material adverse effect on our business. The forward-looking statements made herein speak only as of the date hereof and Mallinckrodt does not assume any obligation to update or revise any forward-looking statement, whether as a result of new information, future events and developments or otherwise, except as required by law. Given these uncertainties, one should not put undue reliance on any forward-looking statements.

Derek Belz

Vice President, Investor Relations

314-654-3950

Media

Joele Frank, Wilkinson Brimmer Katcher

212-355-4449

Mallinckrodt, the “M” brand mark and the Mallinckrodt Pharmaceuticals logo are trademarks of a Mallinckrodt company. Other brands are trademarks of a Mallinckrodt company or their respective owners. © 2024.

Exhibit 99.1