Pace Select Advisors Trust (PREEF) N-CSRSCertified semi-annual shareholder report (management investment company)

PACE^® Select Advisors Trust

Semiannual Report | January 31, 2021

PACE Select Advisors Trust offers multiple share classes representing interests in 15 separate Portfolios. (UBS Government Money Market Investments Fund offers only one share class.) Different classes of shares and/or Portfolios are offered by separate prospectuses.

For more information on a portfolio or class of shares, contact your financial advisor. He or she can send you a current prospectus relating to a portfolio or class of shares. Investors should carefully read and consider a mutual fund's investment objectives, risks, charges, and expenses before investing. The prospectus contains this and other information about a mutual fund. For a current prospectus, contact UBS Asset Management (Americas) Inc. at 888-793 8637, or visit us on the Web at www.ubs.com/am-us.

Derivatives vary in complexity, involve risks which are different from, and may be greater than, the risks associated with investing in securities or other instruments. Please see the funds' prospectuses for more complete discussion of the risks associated with investing in derivatives.

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Introduction

March 12, 2021

Dear PACE Shareholder,

We are pleased to provide you with the semiannual report for the PACE portfolios (the "Portfolios"), comprising the PACE Select Advisors Trust. This report includes summaries of the performance of each Portfolio, as well as commentaries from the investment advisor and subadvisors regarding the events that affected Portfolio performance during the six months ended January 31, 2021 (the "reporting period"). Please note that the opinions of the subadvisors do not necessarily represent those of UBS Asset Management (Americas) Inc.

A global recession and a bounce back

The COVID-19 pandemic as well as governments' various responses drove the global economy during the reporting period, as governments around the world instituted lockdowns in an attempt to stem the spread of the virus. In the US, the full impact of the pandemic was felt in the second quarter of 2020, as gross domestic product ("GDP") was -31.4% as compared to the previous quarter—the steepest decline on record. With large portions of the economy reopening, third quarter GDP growth was 33.4%, the largest increase on record. Finally, the Commerce Department's initial estimate for fourth quarter 2020 annualized GDP growth was 4.0%.

Amid the fallout from COVID-19, the US Federal Reserve Board (the "Fed") took a number of aggressive actions to support the economy and maintain the proper functioning of the financial markets. Looking back, the Fed lowered interest rates twice in March 2020, to a range between 0.00% and 0.25%. Later in the month, the Fed announced it would make unlimited purchases of Treasury and mortgage securities. The Fed also expanded its credit facilities to include the purchase of individual corporate bonds. Finally, at its meeting in September, Fed officials projected that rates could stay anchored near zero through 2023. Central banks outside the US, including the European Central Bank, the Bank of England and the Bank of Japan also maintained highly accommodative monetary policies during the reporting period.

From a global perspective, in its January 2021 World Economic Outlook (WEO) Update, the International Monetary Fund ("IMF") said, "Multiple vaccine approvals and the launch of vaccination in some countries in December have raised hopes of an eventual end to the pandemic. Moreover, economic data released after the October 2020 WEO forecast suggest stronger-than-projected momentum on average across regions in the second half of 2020. Despite the high and rising human toll of the pandemic, economic activity appears to be adapting to subdued contact-intensive activity with the passage of time." From a regional perspective, the IMF projects that 2021 GDP growth in

the eurozone, UK and Japan will be 4.2%, 4.5% and 3.1%, respectively. For comparison purposes, the GDP of these economies were forecast to be -7.2%, -10.0% and -5.1%, respectively, in 2020.

Global equities post robust results

Despite the initial impact from the pandemic and a surge in new strains and virus cases late in the reporting period, the global equity market produced outstanding results during the six-months ended January 31, 2021. US stocks initially moved higher, but then experienced a setback in September and October, partially driven by uncertainties surrounding the November presidential election. A similar dynamic also played out in stock markets overseas. However, global equities then sharply rallied over the last two months of the year, and then posted mixed results in January 2021. This turnaround occurred given the aggressive actions by global central banks and news of several effective COVID-19 vaccines, the resolution of the US election and the long-awaited Brexit agreement. For the six-months ended January 31, 2021, the S&P 500 Index¹ gained 14.47%. Outside the US, international developed equities, as measured by the MSCI EAFE Index (net),² returned 17.58% during the reporting period, while emerging markets equities, as measured by the MSCI Emerging Markets Index (net),³ gained 24.07%.

Riskier fixed income securities outperform

The overall global fixed income market experienced periods of volatility amid periods of both investor risk aversion and risk appetite. In the US, long-term Treasury yields moved higher (bond yields and prices move in the opposite direction). For the six months ended January 31, 2021, the yield on the US 10-year Treasury rose from 0.55% to

¹  The S&P 500 Index is an unmanaged, weighted index composed of 500 widely held common stocks varying in composition and is not available for direct investment. Investors should note that indices do not reflect the deduction of fees and expenses.

²  The MSCI EAFE Index (net) is an index of stocks designed to measure the investment returns of developed economies outside of North America. Net total return indices reinvest dividends after the deduction of withholding taxes, using a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties. The index is constructed and managed with a view to being fully investable from the perspective of international institutional investors. Investors should note that indices do not reflect the deduction of fees and expenses.

³  The MSCI Emerging Markets Index (net) is a market capitalization-weighted index composed of different emerging market countries in Europe, Latin America, and the Pacific Basin. Net total return indices reinvest dividends after the deduction of withholding taxes, using a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties. The index is constructed and managed with a view to being fully investable from the perspective of international institutional investors. Investors should note that indices do not reflect the deduction of fees and expenses.

⁴  The Bloomberg Barclays US Aggregate Index is an unmanaged broad based index designed to measure the US dollar-denominated, investment-grade, taxable bond market. The index includes bonds from the Treasury, government-related, corporate, mortgage-backed, asset-backed and commercial mortgage-backed sectors. Investors should note that indices do not reflect the deduction of fees and expenses.

1.11%. Government bond yields outside the US generally edged higher over the period. The overall US bond market, as measured by the Bloomberg Barclays US Aggregate Index,⁴ returned -0.91% during the reporting period as a whole. Investors who took on more risk were rewarded with better results. High yield bonds, as measured by the ICE BofAML US High Yield Cash Pay Constrained Index,⁵ returned 6.74%. Elsewhere, emerging markets debt, as measured by the J.P. Morgan Emerging Markets Bond Index Global (EMBI Global),⁶ gained 2.79% during the reporting period.

Sincerely,

Igor Lasun
President, PACE Select Advisors Trust
Managing Director, UBS Asset Management (Americas) Inc.

This report is intended to assist investors in understanding how the Portfolios performed during the 6-month period ended January 31, 2021. The views expressed in the Advisor's and Subadvisors' comments sections are as of the end of the reporting period, reflect performance results gross of fees and expenses, and are those of the investment advisor and subadvisors. Subadvisors' comments on Portfolios that have more than one subadvisor are reflective of their portion of the Portfolio only. The views and opinions in this report were current as of March 12, 2021. They are not guarantees of future performance or investment results and should not be taken as investment advice. Investment decisions reflect a variety of factors, and the investment advisor and subadvisors reserve the right to change their views about individual securities, sectors and markets at any time. As a result, the views expressed should not be relied upon as a forecast of a Portfolio's future investment intent.

⁵  The ICE BofAML US High Yield Cash Pay Constrained Index is an unmanaged index of publicly placed, non-convertible, coupon-bearing US dollar denominated, below investment grade corporate debt with a term to maturity of at least one year. The index is market capitalization weighted, so that larger bond issuers have a greater effect on the index's return. However, the representation of any single bond issuer is restricted to a maximum of 2% of the total index. Investors should note that indices do not reflect the deduction of fees and expenses.

⁶  The J.P. Morgan Emerging Markets Bond Index Global (EMBI Global) is an unmanaged index which is designed to track total returns for US dollar denominated debt instruments issued by emerging market sovereign and quasi-sovereign entities: Brady bonds, loans and Eurobonds. Investors should note that indices do not reflect the deduction of fees and expenses.

UBS Government Money Market Investments Fund

Performance

The seven-day current yield for the Fund as of January 31, 2021 was 0.01% (after fee waivers/expense reimbursements).¹ For more information on the Fund's performance, refer to "Yields and characteristics at a glance" on page 7. Please remember that the PACE program fee is assessed outside the Portfolio at the PACE program account level. The program fee does not impact the determination of the Portfolio's net asset value per share. For a detailed commentary on the market environment in general during the period, please refer to page 3.

Advisor's Comments

The US Federal Reserve Board (the "Fed") took a number of aggressive actions to support the economy and maintain the proper functioning of the financial markets. Looking back, the Fed lowered interest rates twice in March 2020, to a range between 0.00% and 0.25%. Later in the month, the Fed announced it would make unlimited purchases of Treasury and mortgage securities. The Fed also expanded its credit facilities to include the purchase of individual corporate bonds. Finally, at its meeting in September, the Fed's dot plot indicated that rates could stay anchored near zero through 2023.

We tactically adjusted the Portfolio's weighted average maturity ("WAM") throughout the six-month review period. When the reporting period began, the Portfolio had a WAM of 53 days. This was 56 days at the end of the reporting period.

A number of adjustments were made to the Portfolio's sector and issuer positioning during the six-month period. We substantially reduced the Portfolio's exposures to US government agency obligations and, to a modest extent, pared its allocation to repurchase agreements. Meanwhile, we substantially increased its position in US Treasury obligations. (Repurchase agreements are transactions in which the seller of a security agrees to buy it back at a predetermined time and price or upon demand.)

Mutual funds are sold by prospectus only. You should read it carefully and consider a fund's investment objectives, risks, charges, expenses and other important information contained in the prospectus before investing. Prospectuses for most of our funds can be obtained from your financial advisor, by calling UBS Funds at 800-647 1568 or by visiting our Website at www.ubs.com/am-us.

¹  Class P shares held through the PACE Select Advisors Program are subject to a maximum Program fee of 2.50%, which, if included, would have reduced performance. Class P shares held through other advisory programs also may be subject to a program fee, which, if included, would have reduced performance.

PACE Select Advisors Trust – UBS Government Money Market Investments Fund (formerly PACE Government Money Market Investments)

Investment Advisor:

UBS Asset Management (Americas) Inc.

Portfolio Manager:

Robert Sabatino

Objective:

Current income consistent with preservation of capital and liquidity

Investment process:

The Portfolio is a money market mutual fund and seeks to maintain a stable price of $1.00 per share, although it may be possible to lose money by investing in this Portfolio. The Portfolio invests in a diversified portfolio of high-quality money market instruments of governmental issuers and in related repurchase agreements. Security selection is based on the assessment of relative values and changes in market and economic conditions.

UBS Government Money Market Investments Fund

Yields and characteristics at a glance—January 31, 2021 (unaudited)

You could lose money by investing in UBS Government Money Market Investments Fund. Although the portfolio seeks to preserve the value of your investment at $1.00 per share, the portfolio cannot guarantee it will do so. An investment in UBS Government Money Market Investments Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation ("FDIC") or any other government agency. UBS Government Money Market Investments Fund's sponsor has no legal obligation to provide financial support to UBS Government Money Market Investments Fund, and you should not expect that the portfolio's sponsor will provide financial support to UBS Government Money Market Investments Fund at any time.

Not FDIC insured. May lose value. No bank guarantee.

¹  Yields will fluctuate and reflect fee waivers and/or expense reimbursements, if any, unless otherwise noted. Performance data quoted represents past performance. Past performance does not guarantee future results. Current performance may be higher or lower than the performance data quoted.

²  The Portfolio is actively managed and its weighted average maturity will differ over time.

³  Weightings represent percentages of the Portfolio's net assets as of the date indicated. The Portfolio is actively managed and its composition will vary over time.

UBS Government Money Market Investments Fund

Portfolio of investments—January 31, 2021 (unaudited)

UBS Government Money Market Investments Fund

Portfolio of investments—January 31, 2021 (unaudited)

For a listing of defined portfolio acronyms that are used throughout the Portfolio of investments as well as the tables that follow, please refer to the Glossary of terms used in the Portfolio of investments.

Fair valuation summary

The following is a summary of the fair valuations according to the inputs used as of January 31, 2021 in valuing the Portfolio's investments. In the event a Portfolio holds investments for which fair value is measured using the NAV per share practical expedient (or its equivalent), a separate column will be added to the fair value hierarchy table; this is intended to permit reconciliation to the amounts presented in the Portfolio of investments:

At January 31, 2021, there were no transfers in or out of Level 3.

Portfolio footnotes

¹  Rate shown is the discount rate at the date of purchase unless otherwise noted.

²  Variable or floating rate security. The interest rate shown is the rate in effect as of period end and changes periodically.

PACE Mortgage-Backed Securities Fixed Income Investments

Performance

For the six-months ended January 31, 2021, the Portfolio's Class P shares returned 1.80% before the deduction of the maximum PACE Select program fee.¹ In comparison, the Bloomberg Barclays US Mortgage-Backed Securities Index (the "benchmark") returned 0.25%. (Returns for all share classes over various time periods are shown in the "Performance at a glance" table on page 12. Please note that the returns shown do not reflect the deduction of taxes that a shareholder would pay on Portfolio distributions or the redemption of Portfolio shares.) For a detailed commentary on the market environment in general during the reporting period, please refer to page 3.

Subadvisor's comments²

The Portfolio outperformed its benchmark during the reporting period. An overall underweight to US duration added to relative performance as Treasury yields rose across the curve. An overweight to agency mortgage-backed securities (MBS) added to results as the sector outperformed like-duration Treasurys over the period. Additionally, relative value positioning within agency MBS, including a focus on Federal Reserve supported coupons, was beneficial for returns. An allocation to senior securitized credit contributed to performance, as these securities remained well-supported by strong fundamentals and limited supply. Additionally, exposure to commercial mortgage-backed securities (CMBS) and select collateralized mortgage obligations (CLOs) added to returns. There were no meaningful detractors from relative performance during the reporting period.

Overall, derivative usage was positive during the period. The use of interest rate swaps to reduce long-end US interest rate exposure contributed to results, as swap rates underperformed relative to Treasury rates. The Fund used interest rate swaps to adjust interest rate and yield curve exposures, as well as to substitute for physical securities. The Portfolio benefited from the income generated from selling mortgage pool options as a way to manage interest rate and volatility risk within the sector. Additionally, options on swaps were primarily used to manage interest rate exposure and volatility. The purchase of options on swaps modestly detracted from performance due to premium payments made. Total return swaps used to replicate broad exposure to interest-only agency mortgages, while limiting idiosyncratic risk of owning individual bonds, was neutral for performance. The use of government futures to adjust interest rate exposures and replicate government bond positions was neutral for returns.

¹  Class P shares held through the PACE Select Advisors Program are subject to a maximum Program fee of 2.50%, which, if included, would have reduced performance. Class P shares held through other advisory programs also may be subject to a program fee, which, if included, would have reduced performance.

²  Performance is discussed on a gross-of-fees basis—meaning that no fees or expenses are reflected when discussed at the level of a subadvisor's sleeve (or subadvisors' sleeves, if applicable). Alternatively, performance at the overall Portfolio level is shown net of fees, which does factor in fees and expenses associated with the Portfolio.

PACE Select Advisors Trust – PACE Mortgage-Backed Securities Fixed Income Investments

Investment Manager:

UBS Asset Management (Americas) Inc. ("UBS AM")

Investment Subadvisor:

Pacific Investment Management Company LLC ("PIMCO")

Portfolio Management Team:

UBS AM: Mabel Lung, CFA, Gina Toth, CFA, Fred Lee, CFA, Joseph Sciortino and Steve Bienashski

PIMCO: Daniel Hyman and Michael Cudzil

Objective:

Current income

Investment process:

The subadvisor utilizes a strategy that involves buying or selling specific bonds based on an analysis of their values relative to other similar bonds.

PACE Mortgage-Backed Securities Fixed Income Investments

Mutual funds are sold by prospectus only. You should read it carefully and consider a fund's investment objectives, risks, charges, expenses and other important information contained in the prospectus before investing. Prospectuses for most of our funds can be obtained from your financial advisor, by calling UBS Funds at 800-647 1568 or by visiting our Website at www.ubs.com/am-us

Special considerations

The Portfolio may be appropriate for long-term investors seeking current income who are able to withstand short-term fluctuations in the fixed income markets in return for potentially higher returns over the long term. The yield and value of the Portfolio change every day and can be affected by changes in interest rates, general market conditions, and other political, social and economic developments, as well as specific matters relating to the issuers in which the Portfolio invests. It is important to note that an investment in the Portfolio is only one component of a balanced investment plan.

PACE Mortgage-Backed Securities Fixed Income Investments

Performance at a glance (unaudited)

Most recent calendar quarter-end returns (unaudited)

The annualized gross and net expense ratios, respectively, for each class of shares as in the November 27, 2020 prospectuses, were as follows: Class A—1.36% and 1.20%; Class Y—1.23% and 0.97%; and Class P—1.18% and 0.95% Net expenses reflect fee waivers and/or expense reimbursements, if any, pursuant to an agreement that is in effect to cap the expenses. The Portfolio and UBS Asset Management (Americas) Inc. ("UBS AM") have entered into a written fee waiver/expense reimbursement agreement pursuant to which UBS AM is contractually obligated to waive its management fees and/or reimburse expenses so that the Portfolio's ordinary total operating expenses of each class through November 30, 2021 (excluding dividend expense, borrowing costs, and interest expense relating to short sales, and expenses attributable to investment in other investment companies, interest, taxes, brokerage commissions and extraordinary expenses) would not exceed Class A—0.97%; Class Y—0.72%; and Class P—0.72%. The Portfolio has agreed to repay UBS AM for any waived fees/reimbursed expenses to the extent that it can do so over the following three fiscal years without causing the Portfolio's expenses in any of those three years to exceed these expense caps and that UBS AM has not waived the right to do so. The fee waiver/expense reimbursement agreement may be terminated by the Portfolio's board at any time and also will terminate automatically upon the expiration or termination of the Portfolio's advisory contract with UBS AM. Upon termination of the agreement, however, UBS AM's three year recoupment rights will survive.

¹  Maximum sales charge for Class A shares is 3.75%. Class A shares bear ongoing 12b-1 service fees of 0.25% annually.

²  The Portfolio offers Class Y shares to a limited group of eligible investors, including certain qualifying retirement plans. Class Y shares do not bear initial or contingent deferred sales charges or ongoing 12b-1 service and distribution fees.

³  Class P shares do not bear initial or contingent deferred sales charges or ongoing 12b-1 service and distribution fees, but Class P shares held through advisory programs may be subject to a program fee, which, if included, would have reduced performance.

⁴  The Bloomberg Barclays US Mortgage-Backed Securities Index is an unmanaged index which primarily covers the mortgage-backed passthrough securities issued by Ginnie Mae (formally known as the Government National Mortgage Association or GNMA), Freddie Mac (formally known as Federal Home Loan Mortgage Corporation or FHLMC), and Fannie Mae (formally known as Federal National Mortgage Association or FNMA). Investors should note that indices do not reflect the deduction of fees and expenses.

Prior to August 3, 2015, a 1% redemption fee was imposed on sales or exchanges of any class of shares of the Portfolio made during the specified holding period.

Past performance does not predict future performance, and the performance information provided does not reflect the deduction of taxes that a shareholder would pay on Portfolio distributions or the redemption of Portfolio shares. The return and principal value of an investment will fluctuate, so that an investor's shares, when redeemed, may be worth more or less than their original cost. Performance results assume reinvestment of all dividends and capital gain distributions at net asset value on the ex-dividend dates. Total returns for periods of less than one year have not been annualized. Current performance may be higher or lower than the performance data quoted. For month-end performance figures, please visit www.ubs.com/us-mutualfundperformance.

Lipper peer group data calculated by Lipper Inc.; used with permission. The Lipper median is the return of the fund that places in the middle of a Lipper peer group.

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio statistics—January 31, 2021 (unaudited)¹

¹  The Portfolio is actively managed and its composition will vary over time.

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio of Investments—January 31, 2021 (unaudited)

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio of Investments—January 31, 2021 (unaudited)

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio of Investments—January 31, 2021 (unaudited)

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio of Investments—January 31, 2021 (unaudited)

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio of Investments—January 31, 2021 (unaudited)

PACE Mortgage-Backed Securities Fixed Income Investments

Portfolio of Investments—January 31, 2021 (unaudited)