Pioneer Asset Allocation Trust NCSR Certified annual shareholder report (management investment company)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED

MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-21569

Pioneer Asset Allocation Trust

(Exact name of registrant as specified in charter)

60 State Street, Boston, MA 02109

(Address of principal executive offices) (ZIP code)

Terrence J. Cullen, Amundi Asset Management, Inc.,

60 State Street, Boston, MA 02109

(Name and address of agent for service)

Registrant’s telephone number, including area code: (617) 742-7825

Date of fiscal year end: July 31, 2021

Date of reporting period: August 1, 2020 through July 31, 2021

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. ss. 3507.

Pioneer Solutions –Balanced Fund

Annual Report | July 31, 2021


A: PIALX	C: PIDCX	R: BALRX	Y: IMOYX

Paper copies of the Fund’s shareholder reports may no longer be sent by mail, unless you specifically request paper copies of the reports from the Fund or from your financial intermediary, such as a broker-dealer, bank or insurance company. Instead, the reports will be made available on the Fund’s website, and you will be notified by mail each time a report is posted and provided with a website link to access the report.

You may elect to receive all future reports in paper free of charge. If you invest directly with the Fund, you can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 1-800-225-6292. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held in your account if you invest through your financial intermediary or all funds held within the Pioneer Fund complex if you invest directly.

visit us: www.amundi.com/us

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 1

President’s Letter

Dear Shareholders,

With the first half of 2021 now behind us, we have seen some better news on the COVID-19 pandemic front. In the US, widespread distribution of the COVID-19 vaccines approved for emergency use late last year, and a general decline in more severe virus cases and related hospitalizations, have had a positive effect on overall market sentiment, even as the emergence of highly infectious variants of the virus in certain areas has led to increased volatility.

While there may finally be a light visible at the end of the pandemic tunnel, the long-term impact on the global economy from COVID-19, while currently unknown, is likely to be considerable. It is clear that several industries have already felt greater effects than others, and the markets, which do not thrive on uncertainty, have been volatile.

With that said, so far during 2021, we have seen investments typically associated with a higher degree of risk, such as equities and high-yield bonds, outperform investments regarded as less risky, such as government debt. In addition, cyclical stocks, or stocks of companies with greater exposure to the ebbs and flows of the economic cycle, have rallied this year after slumping during the height of the pandemic, as investors have appeared to embrace the potential for a more widespread reopening of the economy in the coming months. Additional fiscal stimulus from the US government in recent months has also helped provide some market momentum.

Despite the strong rebound from the March 2020 lows and positive market performance so far this year, several factors that could lead to increased volatility and weaker performance bear watching. These include: public-health issues such as potential surges in COVID-19 cases, particularly as “variants” of the virus have continued to arise; macroeconomic concerns (inflation, energy prices, sluggish employment figures); and changes to the US government’s fiscal policies, particularly the possibility of higher income and capital gains tax rates on both individuals and businesses.

After leaving our offices in March of 2020 due to COVID-19, we have reopened our US locations and have invited our employees to slowly return to the office. I am proud of the careful planning that has taken place. Our business has continued to operate without any disruption and we all look forward to regaining a bit of normalcy after 15 months of remote working.

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Since 1928, Amundi US’s investment process has been built on a foundation of fundamental research and active management, principles which have guided our investment decisions for more than 90 years. We believe active management – that is, making active investment decisions – can help mitigate the risks during periods of market volatility.

At Amundi US, active management begins with our own fundamental, bottom-up research process. Our team of dedicated research analysts and portfolio managers analyzes each security under consideration, communicating directly with the management teams of the companies issuing the securities and working together to identify those securities that best meet our investment criteria for our family of funds. Our risk management approach begins with each and every security, as we strive to carefully understand the potential opportunity, while considering potential risk factors.

Today, as investors, we have many options. It is our view that active management can serve shareholders well, not only when markets are thriving, but also during periods of market stress.

As you consider your long-term investment goals, we encourage you to work with your financial professional to develop an investment plan that paves the way for you to pursue both your short-term and long-term goals.

We greatly appreciate the trust you have placed in us and look forward to continuing to serve you in the future.

Sincerely,

Lisa M. Jones
Head of the Americas, President and CEO of US
Amundi Asset Management US, Inc.
September 2021

Any information in this shareowner report regarding market or economic trends or the factors influencing the Fund’s historical or future performance are statements of opinion as of the date of this report. Past performance is no guarantee of future results.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 3

Portfolio Management Discussion | 7/31/21

In the following interview, portfolio managers Kenneth Taubes and Marco Pirondini discuss the market environment over the 12-month period ended July 31, 2021, and the investment strategies applied to Pioneer Solutions –Balanced Fund during the period. Mr. Taubes, Executive Vice President, Chief Investment Officer, US, and a portfolio manager at Amundi Asset Management US, Inc. (Amundi US), and Mr. Pirondini, Senior Managing Director, Head of Equities, US, and a portfolio manager at Amundi US, are responsible for the day-to-day management of the Fund.

How did the Fund perform during the 12-month period ended July 31, 2021?

The Fund’s Class A shares returned 24.15% at net asset value during the 12-month period ended July 31, 2021, while the Fund’s blended benchmark, which is comprised of 60% Morgan Stanley Capital International (MSCI) World NR Index/40% Bloomberg US Aggregate Bond Index, returned 19.81%. During the same period, the Fund’s market benchmarks, the MSCI World NR Index (the MSCI Index)¹and the Bloomberg US Aggregate Bond Index (the Bloomberg Index), returned 35.07% and -0.70%, respectively, while the average return of the 457 mutual funds in Morningstar’s World Allocation Funds category was 21.10%.

Could you characterize investment conditions in the financial markets during the 12-month period ended July 31, 2021?

The financial markets produced healthy returns over the past 12 months, particularly equities, as a generally favorable news flow fueled investors’ appetite for so-called riskier assets. When the reporting period began in August 2020, the markets were still in the midst of an early rebound from the pandemic-induced lows of the previous March. The combination of sizable fiscal and monetary stimulus from the US government and US

The MSCI information may only be used for your internal use, may not be reproduced or redisseminated in any form and may not be used as a basis for or a component of any financial instruments or products or indices. None of the MSCI information is intended to constitute investment advice or a recommendation to make (or refrain from making) any kind of investment decision and may not be relied on as such. Historical data and analysis should not be taken as an indication or guarantee of any future performance analysis, forecast or prediction. The MSCI information is provided on an “as is” basis and the user of this information assumes the entire risk of any use made of this information. MSCI, each of its affiliates and each other person involved in or related to compiling, computing or creating any MSCI information (collectively, the “MSCI Parties”) expressly disclaims all warranties (including, without limitation, any warranties of originality, accuracy, completeness, timeliness, non-infringement, merchantability and fitness for a particular purpose) with respect to this information. Without limiting any of the foregoing, in no event shall any MSCI Party have any liability for any direct, indirect, special, incidental, punitive, consequential (including, without limitation, lost profits) or any other damages.

4 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Federal Reserve (Fed), as well as indications that the downturn in economic growth might not be as prolonged as first thought, provided firm market support for higher-risk assets. The rally moved another step higher beginning in November 2020 with the announcement that multiple vaccines for COVID-19 had received emergency-use approval from US regulators. That led to further improvement in the outlook for both economic growth and corporate earnings. Financial markets continued to gain ground through the first half of 2021, as the gradual reopening of the global economy after roughly a year of lockdowns and restricted activity outweighed disruptions associated with concerns about rising inflation, the possibility that the Fed could begin tightening monetary policy, and the emergence of the highly infectious COVID-19 “Delta” variant.

Together, those developments fueled unusually large gains for equities. The overall US equity market, as measured by the Standard & Poor’s 500 Index, returned more than 36% for the 12-month period. Domestic small-cap stocks, which have tended to display above-average sensitivity to economic trends, led the way higher among the major equity categories. Large-cap stocks also delivered robust results, but value stocks outpaced growth stocks over the full 12-month period, thanks to the prolonged, five-month stretch of value outperformance in the wake of the vaccine approvals in late 2020. In the international stock markets, developed and emerging markets, while lagging US equities, nonetheless provided strong absolute returns. The slower pace of COVID-19 vaccine distributions (compared to the US) in the countries comprising those markets tended to hold back equity performance, at least to some degree. The prospect of increased regulations in China was an additional headwind for emerging markets stocks.

In the fixed-income markets, accelerating economic growth and concerns about rising inflation resulted in losses for rate-sensitive assets such as long-term US Treasuries over the 12-month period. Conversely, the improving economic outlook led to gains for investment-grade corporates, high-yield bonds, and other credit-oriented market segments.

What factors contributed to and detracted from the Fund’s relative performance during the 12-month period ended July 31, 2021?

The Fund’s relative performance benefited from a sizable portfolio tilt in favor of investments in underlying equity funds, which helped capture some of the significant outperformance of stocks in relation to bonds over

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 5

the 12-month period. The Fund had positions in six funds that, in combination, have tended to invest across the spectrum of US and international stocks, and in the growth and value segments (four US equity funds and two global/international equity funds). Together, those underlying funds delivered strong absolute returns and contributed to the competitive relative performance of the Fund versus the MSCI World Index equity-market benchmark.

The Fund also held large positions in Pioneer Multi-Asset Income Fund and Pioneer Flexible Opportunities Fund, at a combined weighting of approximately 50% of the total investment portfolio. The two underlying funds, which have the flexibility to invest in any segment within the world financial markets, also had heavy weightings in stocks relative to bonds during the period. As a result, each underlying fund delivered returns well in excess of the Fund’s 60/40 composite benchmark, and made a strong positive contribution to relative outperformance for the 12-month period.

The Fund had an allocation to bonds via holdings in three underlying fixed-income funds, comprising about 10% of invested assets, on average. All three underlying funds posted positive returns during the period and outpaced the return of the Bloomberg US Aggregate Bond Index, thus aiding the Fund’s relative performance. Collectively, the underlying fixed-income funds in which we invested the portfolio had allocation tilts towards the credit-oriented areas of the market, and away from US Treasuries and other interest-rate-sensitive investments, which allowed them to capture some of the strong outperformance of credit-sensitive securities during the period. In comparison, Treasuries, which generated a negative return over the 12-month period, represented the largest component of the Bloomberg Index, the Fund’s fixed-income-market benchmark.

The Fund had no investments that materially detracted from benchmark-relative performance during the 12-month period.

Did the Fund have any exposure to derivative securities during the 12-month period ended July 31, 2021? If so, did the derivatives have an effect on the Fund’s performance?

The Fund had no exposure to derivatives during the 12-month period.

6 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Did you make any changes to the Fund’s positioning over the course of the 12-month period ended July 31, 2021?

The portfolio’s allocations remained stable over the 12-month period, due to our belief that the Fund’s positioning could potentially allow performance to benefit from improving economic growth and a generally favorable investment backdrop. However, we did make some changes that are worth noting. First, we increased the Fund’s exposure to international equities, due to what we viewed as their attractive valuations, and we sought to reduce credit risk by eliminating the portfolio’s modest allocation to a high-yield bond fund. The latter shift reflected our view that yield, or credit spreads, relative to US Treasuries had reached such low levels that the risk-and-reward profile for high-yield bonds had become less compelling. (Credit spreads are commonly defined as the differences in yield between Treasuries and other types of fixed-income securities with similar maturities.) We redeployed those proceeds into Pioneer ILS Interval Fund, which invests in insurance-linked securities (ILS). ILS, which allow insurance companies to transfer some of the loss risk associated with insurance claims created by natural disasters to the capital markets, have tended to exhibit risk-and-return characteristics largely independent of the broader fixed-income market. As such, we think exposure to ILS through the underlying portfolio may provide the Fund with an attractive source of diversification*.

What factors are you watching most closely as you determine the Fund’s investment strategy heading into the new fiscal year?

We believe a long-term approach that combines top-down views and bottom-up analysis to drive asset allocation decisions is the most appropriate investment course, given the Fund’s objectives. Our core view is that stocks have remained a more compelling option than bonds, as we feel the current low yields available have not been providing fixed-income investors with adequate compensation for assuming the underlying risks.

Even though equities have rallied significantly in the past year, the forward earnings yields of companies that are components of the Standard & Poor’s 500 Index (in other words, earnings divided by price) have remained higher than investment-grade corporate bond yields. With that said, we have retained an allocation to underlying bond funds in the portfolio, for diversification purposes.

* Diversification does not assure a profit nor protect against loss.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 7

Overall, the Fund’s investments have remained globally diversified through ownership of underlying funds that invest in asset categories across both the US and foreign markets.

Please refer to the Schedule of Investments on pages 22–23 for a full listing of fund securities.

All investments are subject to risk, including the possible loss of principal. In the past several years, financial markets have experienced increased volatility and heightened uncertainty. The market prices of securities may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues or adverse investor sentiment. These conditions may continue, recur, worsen or spread.

The Fund is a “fund-of-funds” which seeks to achieve its investment objectives by investing primarily in funds managed by Amundi US, rather than making direct investments in securities. The Fund’s performance depends on the adviser’s skill in determining the strategic asset allocations, the mix of underlying funds, as well as the performance of those underlying funds. The underlying funds’ performance may be lower than the performance of the asset class that they were selected to represent. In addition to the Fund’s operating expenses, investors will indirectly bear the operating expenses of investments in any underlying funds. Each of the underlying funds has its own investment risks.

At times, the Fund’s investments may represent industries or sectors that are interrelated or have common risks, making them more susceptible to any economic, political, or regulatory developments or other risks affecting those industries and sectors. Investments in equity securities are subject to price fluctuation.

When interest rates rise, the prices of fixed income securities held by the underlying funds will generally fall. Conversely, when interest rates fall, the prices of fixed income securities held by underlying funds will generally rise.

Investments in the Fund are subject to possible loss due to the financial failure of issuers of underlying securities and their inability to meet their debt obligations.

Investing in foreign and/or emerging markets securities involves risks relating to interest rates, currency exchange rates, economic, and political conditions.

8 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Some of the underlying funds may invest in real estate investment trust (REIT) securities, the value of which can fall for a variety of reasons, such as declines in rental income, fluctuating interest rates, poor property management, environmental liabilities, uninsured damage, increased competition, or changes in real estate tax laws.

The Fund may invest in underlying funds with exposure to commodities. The value of commodity-linked derivatives may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, factors affecting a particular industry or commodity, international economic, political and regulatory developments, supply and demand, and governmental regulatory policies.

Certain of the underlying funds in which the Fund invests may use derivatives, which subject the funds to additional risk.

Some of the underlying funds employ leverage, which increases the volatility of investment returns and subjects the Fund to magnified losses if an underlying fund’s investments decline in value. Some of the underlying funds may employ short selling, a speculative strategy. Unlike the possible loss on a security that is purchased, there is no limit on the amount of loss on an appreciating security that is sold short.

The value of the investments held by the Fund for cash management or temporary defensive purposes may be affected by market risks, changing interest rates, and by changes in credit ratings of the investments. If the Fund holds cash uninvested, the Fund will not earn income on the cash and the Fund’s yield will go down. These risks may increase share price volatility.

There is no assurance that these and other strategies used by the Fund will be successful. Please see the prospectus for a more complete discussion of the Fund’s risks.

Before making an investment in any fund, you should consider all the risks associated with it.

Before investing, consider the product’s investment objectives, risks, charges and expenses. Contact your financial professional or Amundi Asset Management US, Inc., for a prospectus or summary prospectus containing this information. Read it carefully.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 9

Portfolio Summary | 7/31/21

Asset Allocations

(As a percentage of total investments)*

Actual Portfolio Holdings

(As a percentage of total investments)*


Balanced/Flexible
Pioneer Multi-Asset Income Fund Class K	30.03%
Pioneer Flexible Opportunities Fund
Class K	20.09
International Equities
Pioneer Global Equity Fund Class K	14.97%
Pioneer International Equity Fund Class Y	13.43


Fixed Income
Pioneer Multi-Asset Ultrashort Income
Fund Class K	10.97%
Pioneer ILS Interval Fund	2.56
Pioneer Strategic Income Fund Class K	0.52
Pioneer Bond Fund Class K	0.01
U.S. Equities
Pioneer Core Equity Fund Class K	2.68%
Pioneer Equity Income Fund Class K	2.58
Pioneer Fundamental Growth Fund Class K	1.10
Pioneer Fund Class K	1.06

Annual and semiannual reports for the underlying Pioneer funds may be obtained on the funds’ web page(s) at www.amundi.com/us.

Excludes temporary cash investments and all derivative contracts except for options purchased. The Fund is actively managed, and current holdings may be different. The holdings listed should not be considered recommendations to buy or sell any securities.

10 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Prices and Distributions | 7/31/21

Net Asset Value per Share


Class	7/31/21	7/31/20
A	$13.20	$10.93
C	$11.99	$9.94
R	$13.10	$10.86
Y	$13.42	$11.11

Distributions per Share: 8/1/20–7/31/21


	Net Investment	Short-Term	Long-Term
Class	Income	Capital Gains	Capital Gains
A	$0.2627	$0.0231	$0.0500
C	$0.1732	$0.0231	$0.0500
R	$0.2576	$0.0231	$0.0500
Y	$0.2922	$0.0231	$0.0500

Index Definitions

The Morgan Stanley Capital International (MSCI) World NR Index is an unmanaged measure of the performance of stock markets in the developed world. The Bloomberg US Aggregate Bond Index is an unmanaged measure of the U.S. bond market. Index returns are calculated monthly, assume reinvestment of dividends and, unlike Fund returns, do not reflect any fees, expenses or sales charges. It is not possible to invest directly in an index.

The indices defined here pertain to the “Value of $10,000 Investment” and “Value of $5 Million Investment” charts on pages 12–19.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 11


Performance Update \| 7/31/21	Class A Shares

Investment Returns

The mountain chart below shows the change in value of a $10,000 investment made in Class A shares of Pioneer Solutions – Balanced Fund at public offering price during the periods shown, compared to that of the MSCI World NR Index, the Bloomberg US Aggregate Bond Index, and the Fund’s blended benchmark.

Average Annual Total Returns

(As of July 31, 2021)

		Public			60% MSCI World NR
	Net Asset	Offering		Bloomberg	Index/40% Bloomberg
	Value	Price	MSCI World	US Aggregate	US Aggregate
Period	(NAV)	(POP)	NR Index	Bond Index	Bond Index
10 years	5.98%	5.35%	11.05%	3.35%	8.17%
5 years	7.00	5.74	14.29	3.13	9.99
1 year	24.15	17.01	35.07	-0.70	19.81

Expense Ratio

(Per prospectus dated December 1, 2020)

Gross

1.14%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

The performance data quoted represents past performance, which is no guarantee of future results. Investment return and principal value will fluctuate, and shares, when redeemed, may be worth more or less than their original cost.

(Please see the following page for additional performance and expense disclosure)

12 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

NAV results represent the percent change in net asset value per share. POP returns reflect deduction of the maximum 5.75% sales charge. NAV returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.

Performance results shown reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.

Please see the financial highlights for a more recent expense ratio. Expense ratios in the financial highlights, unlike those shown in the prospectus, do not reflect acquired fund fees and expenses.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Effective November 17, 2014, Amundi US became directly responsible for portfolio management of the Fund. The performance shown for periods prior to November 17, 2014, reflects the investment strategies employed during those periods.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 13


Performance Update \| 7/31/21	Class C Shares

Investment Returns

The mountain chart below shows the change in value of a $10,000 investment made in Class C shares of Pioneer Solutions – Balanced Fund during the periods shown, compared to that of the MSCI World NR Index, the Bloomberg US Aggregate Bond Index, and the Fund’s blended benchmark.

Average Annual Total Returns

(As of July 31, 2021)

					60% MSCI World NR
				Bloomberg	Index/40% Bloomberg
	If	If	MSCI World	US Aggregate	US Aggregate
Period	Held	Redeemed	NR Index	Bond Index	Bond Index
10 years	5.22%	5.22%	11.05%	3.35%	8.17%
5 years	6.24	6.24	14.29	3.13	9.99
1 year	23.34	23.34	35.07	-0.70	19.81

Expense Ratio

(Per prospectus dated December 1, 2020)

Gross

1.82%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

(Please see the following page for additional performance and expense disclosure)

14 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Class C shares held for less than one year are also subject to a 1% contingent deferred sales charge (CDSC). “If Held” results represent the percent change in net asset value per share. NAV returns would have been lower had sales charges been reflected. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.

Please see the financial highlights for a more recent expense ratio. Expense ratios in the financial highlights, unlike those shown in the prospectus, do not reflect acquired fund fees and expenses.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 15

Performance Update | 7/31/21

Class R Shares

Investment Returns

The mountain chart below shows the change in value of a $10,000 investment made in Class R shares of Pioneer Solutions – Balanced Fund during the periods shown, compared to that of the MSCI World NR Index, the Bloomberg US Aggregate Bond Index, and the Fund’s blended benchmark.


Average Annual Total Returns
(As of July 31, 2021)
				60% MSCI World NR
	Net Asset		Bloomberg	Index/40% Bloomberg
	Value	MSCI World	US Aggregate	US Aggregate
Period	(NAV)	NR Index	Bond Index	Bond Index
10 years	5.84%	11.05%	3.35%	8.17%
5 years	6.78	14.29	3.13	9.99
1 year	23.97	35.07	-0.70	19.81

Expense Ratio

(Per prospectus dated December 1, 2020)

Gross

1.27%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

(Please see the following page for additional performance and expense disclosure)

16 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

The performance shown for Class R shares for the period prior to the commencement of operations of Class R shares on July 1, 2015, is the net asset value performance of the Fund’s Class A shares, which has not been restated to reflect any differences in expenses, including Rule 12b-1 fees applicable to Class A shares. Since fees for Class A shares generally are higher than those of Class R shares, the performance of Class R shares prior to their inception would have been higher than the performance shown. For the period beginning July 1, 2015, the actual performance of Class R shares is reflected. Class R shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors. All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.

Performance results reflect any applicable expense waivers in effect during the periods shown. Without such waivers Fund performance would be lower. Waivers may not be in effect for all funds. Certain fee waivers are contractual through a specified period. Otherwise, fee waivers can be rescinded at any time. See the prospectus and financial statements for more information.

Please see the financial highlights for more recent expense ratios. Expense ratios in the financial highlights, unlike those shown in the prospectus, do not reflect acquired fund fees and expenses.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 17


Performance Update \| 7/31/21	Class Y Shares

Investment Returns

The mountain chart below shows the change in value of a $5 million investment made in Class Y shares of Pioneer Solutions – Balanced Fund during the periods shown, compared to that of the MSCI World NR Index, the Bloomberg US Aggregate Bond Index, and the Fund’s blended benchmark.

Average Annual Total Returns
(As of July 31, 2021)

				60% MSCI World NR
	Net Asset		Bloomberg	Index/40% Bloomberg
	Value	MSCI World	US Aggregate	US Aggregate
Period	(NAV)	NR Index	Bond Index	Bond Index
10 years	6.23%	11.05%	3.35%	8.17%
5 years	7.23	14.29	3.13	9.99
1 year	24.41	35.07	-0.70	19.81

Expense Ratio

(Per prospectus dated December 1, 2020)

Gross

0.90%

Call 1-800-225-6292 or visit www.amundi.com/us for the most recent month-end performance results. Current performance may be lower or higher than the performance data quoted.

(Please see the following page for additional performance and expense disclosure)

18 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Class Y shares are not subject to sales charges and are available for limited groups of eligible investors, including institutional investors.

All results are historical and assume the reinvestment of dividends and capital gains. Other share classes are available for which performance and expenses will differ.

Please see the financial highlights for a more recent expense ratio. Expense ratios in the financial highlights, unlike those shown in the prospectus, do not reflect acquired fund fees and expenses.

The performance table and graph do not reflect the deduction of fees and taxes that a shareowner would pay on Fund distributions or the redemption of Fund shares.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 19

Comparing Ongoing Fund Expenses

As a shareowner in the Fund, you incur two types of costs:

(1)

ongoing costs, including management fees, distribution and/or service (12b-1) fees, and other Fund expenses; and

(2)

transaction costs, including sales charges (loads) on purchase payments.

This example is intended to help you understand your ongoing expenses (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 at the beginning of the Fund’s latest six-month period and held throughout the six months.

Using the Tables

Actual Expenses

The first table below provides information about actual account values and actual expenses. You may use the information in this table, together with the amount you invested, to estimate the expenses that you paid over the period as follows:

(1)

Divide your account value by $1,000

Example: an $8,600 account value ÷ $1,000 = 8.6

(2)

Multiply the result in (1) above by the corresponding share class’s number in the third row under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Expenses Paid on a $1,000 Investment in Pioneer Solutions Balanced Fund

Based on actual returns from February 1, 2021 through July 31, 2021.


Share Class	A	C	R	Y
Beginning Account	$1,000.00	$1,000.00	$1,000.00	$1,000.00
Value on 2/1/21
Ending Account Value	$1,099.06	$1,095.97	$1,098.05	$1,100.00
(after expenses)
on 7/31/21
Expenses Paid	$2.39	$6.13	$3.28	$0.99
During Period*

Expenses are equal to the Fund’s annualized net expense ratio of 0.46%, 1.18%, 0.63% and 0.19%, for Class A, Class C, Class R and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 181/365 to reflect the one half-year period. Fund expense ratios do not include estimates for acquired fund fees and expenses (AFFE). If AFFE estimates were included, expenses paid during the period would have been $5.83, $9.56, $6.71 and $4.43 for Class A, Class C, Class R and Class Y shares, respectively, based on the respective expense ratio for each class of 1.12%, 1.84%, 1.29% and 9.85%.

20 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Hypothetical Example for Comparison Purposes

The table below provides information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period.

You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the tables are meant to highlight your ongoing costs only and do not reflect any transaction costs, such as sales charges (loads) that are charged at the time of the transaction. Therefore, the table below is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher.

Expenses Paid on a $1,000 Investment in Pioneer Solutions Balanced Fund

Based on a hypothetical 5% per year return before expenses, reflecting the period from February 1, 2021 through July 31, 2021.


Share Class	A	C	R	Y
Beginning Account	$1,000.00	$1,000.00	$1,000.00	$1,000.00
Value on 2/1/21
Ending Account Value	$1,022.51	$1,018.94	$1,021.67	$1,023.85
(after expenses)
on 7/31/21
Expenses Paid	$2.31	$5.91	$3.16	$0.95
During Period*

Expenses are equal to the Fund’s annualized net expense ratio of 0.46%, 1.18%, 0.63% and 0.19%, for Class A, Class C, Class R and Class Y shares, respectively, multiplied by the average account value over the period, multiplied by 181/365 to reflect the one half-year period. Fund expense ratios do not include estimates for acquired fund fees and expenses (AFFE). If AFFE estimates were included, expenses paid during the period would have been $5.61, $9.20, $6.46 and $4.26 for Class A, Class C, Class R and Class Y shares, respectively, based on the respective expense ratio for each class of 1.12%, 1.84%, 1.29% and 9.85%.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 21

Schedule of Investments | 7/31/21

			Change
			in Net
		Net	Unrealized	Capital
		Realized	Appreciation	Gain	Dividend
Shares		Gain (Loss)	(Depreciation)	Distributions	Income	Value
	AFFILIATED ISSUERS — 99.2%*
	MUTUAL FUNDS — 96.7%
5,866	Pioneer Bond Fund Class K $ 282,179		$ (86,381)	$ 10,835	$ 213,223	$ 59,831
464,002	Pioneer Core Equity Fund	650,302	2,400,624	1,193,985	142,880	12,226,465
	Class K
282,279	Pioneer Equity Income	129,843	2,884,218	—	198,522	11,714,577
	Fund Class K
6,411,819	Pioneer Flexible	(134,837)	18,218,328	—	944,510	91,368,416
	Opportunities Fund
	Class K
115,628	Pioneer Fund Class K	1,742,518	463,653	582,718	13,456	4,835,560
138,835	Pioneer Fundamental	1,387,456	(105,932)	878,704	17,115	4,995,271
	Growth Fund Class K
3,306,129	Pioneer Global Equity	831,633	18,528,856	—	758,947	68,106,261
	Fund Class K
2,199,787	Pioneer International	658,111	14,269,086	—	328,801	61,088,085
	Equity Fund Class Y
11,365,541	Pioneer Multi-Asset	(641,054)	18,348,939	—	6,878,581	136,613,806
	Income Fund Class K
5,119,318	Pioneer Multi-Asset	(302,838)	573,395	—	351,594	49,862,157
	Ultrashort Income
	Fund Class K
206,140	Pioneer Strategic Income	1,794,837	(1,047,411)	—	514,613	2,362,368
	Fund Class K
	Other affiliated securities	3,525	249,136	—	190,905	—
	not held at year end
	TOTAL MUTUAL FUNDS
	(Cost $370,772,754)	$6,401,675	$74,696,511	$ 2,666,242	$10,553,147	$ 443,232,797
	CLOSED-END FUND — 2.5%
1,345,927	Pioneer ILS Interval Fund	—	255,728	—	—	11,655,729
	TOTAL CLOSED-END FUND
	(Cost $11,400,001)	$ —	$ 255,728	$ —	$ —	$ 11,655,729
	INVESTMENTS IN AFFILIATED ISSUERS
	(Cost $382,172,755)	$6,401,675	$74,952,239	$ 2,666,242	$10,553,147	$ 454,888,526
	OTHER ASSETS AND LIABILITIES — 0.8%					$ 3,445,687
	TOTAL NET ASSETS — 100.0%					$ 458,334,213

* Affiliated funds managed by Amundi Asset Management US, Inc. (the “Adviser”).

The accompanying notes are an integral part of these financial statements.

22 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Purchases and sales of securities (excluding temporary cash investments) for the year ended July 31, 2021, aggregated $104,387,466 and $126,007,934, respectively.

The Fund is permitted to engage in purchase and sale transactions (“cross trades”) with certain funds and accounts for which the Adviser serves as the Fund’s investment adviser, as set forth in Rule 17a-7 under the Investment Company Act of 1940, pursuant to procedures adopted by the Board of Trustees. Under these procedures, cross trades are effected at current market prices. During the year ended July 31, 2021, the Fund did not engage in any cross trade activity.

At July 31, 2021, the net unrealized appreciation on investments based on cost for federal tax purposes of $385,740,120 was as follows:

Aggregate gross unrealized appreciation for all investments in which
there is an excess of value over tax cost	$ 72,715,771
Aggregate gross unrealized depreciation for all investments in which
there is an excess of tax cost over value	(3,567,365)
Net unrealized appreciation	$ 69,148,406

Various inputs are used in determining the value of the Fund’s investments. These inputs are summarized in the three broad levels below.

Level 1 –

quoted prices in active markets for identical securities.

Level 2 –

other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risks, etc.). See Notes to Financial Statements — Note 1A.

Level 3 –

significant unobservable inputs (including the Fund’s own assumptions in determining fair value of investments). See Notes to Financial Statements — Note 1A.

The following is a summary of the inputs used as of July 31, 2021, in valuing the Fund's assets:


	Level 1	Level 2	Level 3	Total
Affiliated Mutual Funds	$443,232,797	$11,655,729	$ —	$454,888,526
Total	$443,232,797	$11,655,729	$ —	$454,888,526

During the year ended July 31, 2021, there were no transfers in or out of Level 3.

The accompanying notes are an integral part of these financial statements.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 23

Statement of Assets and Liabilities | 7/31/21

ASSETS:
Investments in securities of affiliated funds, at value (cost $382,172,755)	$ 454,888,526
Cash	9,548,360
Receivables —
Fund shares sold	49,637
Dividends	627,426
Other assets	35,249
Total assets	$ 465,149,198
LIABILITIES:
Payables —
Investment securities purchased	$ 6,609,508
Fund shares repurchased	65,280
Trustees’ fees	1,218
Due to affiliates	11,727
Accrued expenses	127,252
Total liabilities	$ 6,814,985
NET ASSETS:
Paid-in capital	$ 376,422,741
Distributable earnings	81,911,472
Net assets	$ 458,334,213
NET ASSET VALUE PER SHARE:
No par value (unlimited number of shares authorized)
Class A (based on $395,303,171/29,952,407 shares)	$ 13.20
Class C (based on $58,428,217/4,874,477 shares)	$ 11.99
Class R (based on $1,869,797/142,753 shares)	$ 13.10
Class Y (based on $2,733,028/203,596 shares)	$ 13.42
MAXIMUM OFFERING PRICE PER SHARE:
Class A (based on $13.20 net asset value per share/100%-5.75%
maximum sales charge)	$ 14.01

The accompanying notes are an integral part of these financial statements.

24 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Statement of Operations

FOR THE YEAR ENDED 7/31/21


INVESTMENT INCOME:
Dividend income from underlying affiliated funds	$10,553,147
Dividends from unaffiliated issuers (net of foreign taxes
withheld $742)	11,905
Interest	157
Total investment income		$10,565,209
EXPENSES:
Administrative expense	$ 210,372
Transfer agent fees
Class A	295,055
Class C	34,098
Class R	179
Class Y	1,133
Distribution fees
Class A	929,551
Class C	603,520
Class R	8,455
Shareowner communications expense	129,878
Custodian fees	9,699
Registration fees	65,648
Professional fees	70,092
Printing expense	61,913
Trustees' fees	15,873
Insurance expense	685
Miscellaneous	16,842
Total expenses		$ 2,452,993
Net investment income		$ 8,112,216
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:
Net realized gain (loss) on:
Investments in unaffiliated issuers	$ 170,477
Investments in underlying affiliated funds	6,401,675
Capital gain on distributions from underlying
affiliated issuers	2,666,242	$ 9,238,394
Change in net unrealized appreciation (depreciation) on:
Investments in unaffiliated issuers	$ (32,076)
Investments in underlying affiliated funds	74,952,239	$74,920,163
Net realized and unrealized gain (loss) on investments		$84,158,557
Net increase in net assets resulting from operations		$92,270,773

The accompanying notes are an integral part of these financial statements.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 25

Statements of Changes in Net Assets


	Year	Year
	Ended	Ended
	7/31/21	7/31/20
FROM OPERATIONS:
Net investment income (loss)	$ 8,112,216	$ 12,312,706
Net realized gain (loss) on investments	9,238,394	865,387
Change in net unrealized appreciation (depreciation)
on investments	74,920,163	(2,607,274)
Net increase in net assets resulting from operations	$ 92,270,773	$ 10,570,819
DISTRIBUTIONS TO SHAREOWNERS:
Class A ($0.33 and $0.72 per share, respectively)	$ (10,156,686)	$ (21,592,985)
Class C ($0.24 and $0.64 per share, respectively)	(1,258,078)	(4,366,055)
Class R ($0.33 and $0.67 per share, respectively)	(46,785)	(60,137)
Class Y ($0.36 and $0.75 per share, respectively)	(50,353)	(99,948)
Total distributions to shareowners	$ (11,511,902)	$ (26,119,125)
FROM FUND SHARE TRANSACTIONS:
Net proceeds from sales of shares	$ 39,686,202	$ 34,711,645
Reinvestment of distributions	11,400,298	25,829,400
Cost of shares repurchased	(69,589,068)	(77,488,192)
Net decrease in net assets resulting from Fund
share transactions	$ (18,502,568)	$ (16,947,147)
Net increase (decrease) in net assets	$ 62,256,303	$ (32,495,453)
NET ASSETS:
Beginning of year	$ 396,077,910	$428,573,363
End of year	$ 458,334,213	$396,077,910

The accompanying notes are an integral part of these financial statements.

26 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21


	Year Ended	Year Ended	Year Ended	Year Ended
	7/31/21	7/31/21	7/31/20	7/31/20
	Shares	Amount	Shares	Amount
Class A
Shares sold	2,508,303	$ 30,797,086	2,322,942	$ 25,014,421
Reinvestment of distributions	838,102	10,057,167	1,899,167	21,346,642
Less shares repurchased	(3,663,333)	(44,958,789)	(4,908,594)	(52,937,950)
Net decrease	(316,928)	$ (4,104,536)	(686,485)	$ (6,576,887)
Class C
Shares sold	618,715	$ 6,886,407	769,027	$ 7,623,341
Reinvestment of distributions	114,363	1,251,153	422,177	4,331,539
Less shares repurchased	(2,115,255)	(23,399,577)	(2,346,360)	(23,039,813)
Net decrease	(1,382,177)	$(15,262,017)	(1,155,156)	$(11,084,933)
Class R
Shares sold	27,450	$ 338,980	63,975	$ 644,248
Reinvestment of distributions	3,925	46,785	5,384	60,137
Less shares repurchased	(36,160)	(430,273)	(9,573)	(104,647)
Net increase (decrease)	(4,785)	$ (44,508)	59,786	$ 599,738
Class Y
Shares sold	129,132	$ 1,663,729	132,410	$ 1,429,635
Reinvestment of distributions	3,711	45,193	7,983	91,082
Less shares repurchased	(62,425)	(800,429)	(143,468)	(1,405,782)
Net increase (decrease)	70,418	$ 908,493	(3,075)	$ 114,935

The accompanying notes are an integral part of these financial statements.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 27

Financial Highlights

	Year			Year			Year			Year			Year
	Ended			Ended			Ended			Ended			Ended
	7/31/21			7/31/20			7/31/19			7/31/18			7/31/17
Class A
Net asset value, beginning of period	$	10.93		$	11.29		$	12.12		$	11.89		$	11.35
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$	0.24		$	0.34		$	0.32		$	0.20		$	0.17
Net realized and unrealized gain (loss) on investments		2.36			0.02			(0.54	)		0.25			0.61
Net increase (decrease) from investment operations	$	2.60		$	0.36		($	0.22	)	$	0.45		$	0.78
Distributions to shareowners:
Net investment income	($	0.26	)	($	0.36	)	($	0.34	)	($	0.22	)	($	0.24	)
Net realized gain		(0.07	)		(0.36	)		(0.27	)		—			—
Total distributions	($	0.33	)	($	0.72	)	($	0.61	)	($	0.22	)	($	0.24	)
Net increase (decrease) in net asset value	$	2.27		($	0.36	)	($	0.83	)	$	0.23		$	0.54
Net asset value, end of period	$	13.20		$	10.93		$	11.29		$	12.12		$	11.89
Total return (b)		24.15	%		3.06	%		(1.32	%)		3.79	%		7.04	%
Ratio of net expenses to average net assets†		0.46	%		0.49	%		0.45	%		0.57	%		0.68	%
Ratio of net investment income (loss) to average net assets†^		1.95	%		3.16	%		2.82	%		1.67	%		1.51	%
Portfolio turnover rate		24	%		30	%		44	%		146	%		27	%
Net assets, end of period (in thousands)	$	395,303		$	330,784		$	349,505		$	382,265		$	114,528

†

In addition to the expenses which the Fund bears directly, the Fund indirectly bears pro rata shares of the expenses of the funds in which the Fund invests. Because each of the underlying funds bears its own varying expense levels and because the Fund may own differing proportions of each fund at different times, the amount of expenses incurred indirectly by the Fund will vary from time to time.

Ratios do not reflect the Fund’s proportionate share of the income and expenses of the underlying funds.

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions, the complete redemption of the investment at net asset value at the end of each period and no sales charges. Total return would be reduced if sales charges were taken into account.

The accompanying notes are an integral part of these financial statements.

28 Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21

	Year			Year			Year			Year			Year
	Ended			Ended			Ended			Ended			Ended
	7/31/21			7/31/20			7/31/19			7/31/18			7/31/17
Class C
Net asset value, beginning of period	$	9.94		$	10.32		$	11.12		$	10.92		$	10.44
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$	0.14		$	0.25		$	0.20		$	0.15		$	0.09
Net realized and unrealized gain (loss) on investments		2.15			0.01			-0.49			0.19			0.55
Net increase (decrease) from investment operations	$	2.29		$	0.26		($	0.29	)	$	0.34		$	0.64
Distributions to shareowners:
Net investment income	($	0.17	)	($	0.28	)	($	0.24	)	($	0.14	)	($	0.16	)
Net realized gain		(0.07	)		(0.36	)		(0.27	)		—			—
Total distributions	($	0.24	)	($	0.64	)	($	0.51	)	($	0.14	)	($	0.16	)
Net increase (decrease) in net asset value	$	2.05		($	0.38	)	($	0.80	)	$	0.20		$	0.48
Net asset value, end of period	$	11.99		$	9.94		$	10.32		$	11.12		$	10.92
Total return (b)		23.34	%		2.35	%		(2.14	%)		3.09	%		6.26	%
Ratio of net expenses to average net assets†		1.18	%		1.17	%		1.19	%		1.27	%		1.38	%
Ratio of net investment income (loss) to average net assets†^		1.29	%		2.50	%		1.96	%		1.33	%		0.84	%
Portfolio turnover rate		24	%		30	%		44	%		146	%		27	%
Net assets, end of period (in thousands)	$	58,428		$	62,213		$	76,524		$	114,266		$	49,277

†

Ratios do not reflect the Fund's proportionate share of the income and expenses of the underlying funds.

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

Assumes initial investment at net asset value at the beginning of each period, reinvestment of all distributions and the complete redemption of the investment at net asset value at the end of each period.

The accompanying notes are an integral part of these financial statements.

Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21 29

Financial Highlights (continued)


	Year			Year			Year			Year			Year
	Ended			Ended			Ended			Ended			Ended
	7/31/21			7/31/20			7/31/19			7/31/18			7/31/17
Class R
Net asset value, beginning of period	$	10.86		$	11.19		$	12.04		$	11.83		$	11.30
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$	0.22		$	0.31		$	0.23		$	0.05		$	0.11
Net realized and unrealized gain (loss) on investments		2.35			0.03			(0.49	)		0.37			0.65
Net increase (decrease) from investment operations	$	2.57		$	0.34		$	(0.26	)	$	0.42		$	0.76
Distributions to shareowners:
Net investment income	$	(0.26	)	$	(0.31	)	$	(0.32	)	$	(0.21	)	$	(0.23	)
Net realized gain		(0.07	)		(0.36	)		(0.27	)		—			—
Total distributions	$	(0.33	)	$	(0.67	)	$	(0.59	)	$	(0.21	)	$	(0.23	)
Net increase (decrease) in net asset value	$	2.24		$	(0.33	)	$	(0.85	)	$	0.21		$	0.53
Net asset value, end of period	$	13.10		$	10.86		$	11.19		$	12.04		$	11.83
Total return (b)		23.97	%		2.90	%		(1.64	)%		3.49	%		6.89	%
Ratio of net expenses to average net assets†		0.63	%		0.62	%		0.78	%		0.79	%		0.90	%
Ratio of net investment income (loss) to average net assets†^		1.82	%		2.86	%		2.05	%		0.42	%		0.98	%
Portfolio turnover rate		24	%		30	%		44	%		146	%		27	%
Net assets, end of period (in thousands)	$	1,870		$	1,602		$	982		$	1,388		$	31
Ratios with no waiver of fees and assumption of expenses by
the Adviser and no reduction for fees paid indirectly:
Total expenses to average net assets†		0.63	%		0.62	%		1.03	%		0.86	%		1.38	%
Net investment income (loss) to average net assets^		1.82	%		2.86	%		1.80	%		0.35	%		0.50	%

†

Ratios do not reflect the Fund's proportionate share of the income and expenses of the underlying funds.

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

The accompanying notes are an integral part of these financial statements.

30 Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21

	Year			Year			Year			Year			Year
	Ended			Ended			Ended			Ended			Ended
	7/31/21			7/31/20			7/31/19			7/31/18			7/31/17
Class Y
Net asset value, beginning of period	$	11.11		$	11.46		$	12.29		$	12.06		$	11.51
Increase (decrease) from investment operations:
Net investment income (loss) (a)	$	0.26		$	0.38		$	0.39		$	0.26		$	0.19
Net realized and unrealized gain (loss) on investments		2.41			0.02			(0.59	)		0.22			0.63
Net increase (decrease) from investment operations	$	2.67		$	0.40		$	(0.20	)	$	0.48		$	0.82
Distributions to shareowners:
Net investment income	$	(0.29	)	$	(0.39	)	$	(0.36	)	$	(0.25	)	$	(0.27	)
Net realized gain		(0.07	)		(0.36	)		(0.27	)		—			—
Total distributions	$	(0.36	)	$	(0.75	)	$	(0.63	)	$	(0.25	)	$	(0.27	)
Net increase (decrease) in net asset value	$	2.31		$	(0.35	)	$	(0.83	)	$	0.23		$	0.55
Net asset value, end of period	$	13.42		$	11.11		$	11.46		$	12.29		$	12.06
Total return (b)		24.41	%		3.31	%		(1.14	)%		3.94	%		7.33	%
Ratio of net expenses to average net assets†		0.19	%		0.25	%		0.27	%		0.40	%		0.47	%
Ratio of net investment income (loss) to average net assets†^		2.06	%		3.44	%		3.37	%		2.14	%		1.67	%
Portfolio turnover rate		24	%		30	%		44	%		146	%		27	%
Net assets, end of period (in thousands)	$	2,733		$	1,479		$	1,562		$	1,547		$	698

†

Ratios do not reflect the Fund's proportionate share of the income and expenses of the underlying funds.

(a)

The per-share data presented above is based on the average shares outstanding for the period presented.

(b)

The accompanying notes are an integral part of these financial statements.

Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21 31

Notes to Financial Statements | 7/31/21

1. Organization and Significant Accounting Policies

Pioneer Solutions - Balanced Fund (the “Fund”) is the sole series of Pioneer Asset Allocation Trust (the “Trust”), a Delaware statutory trust. The Fund is registered with the Securities and Exchange Commission under the Investment Company Act of 1940 as an open-end management investment company. The investment objective of the Fund is to seek long-term capital growth and current income.

The Fund is a “fund of funds”. The Fund seeks to achieve its investment objective by investing primarily in other funds (“underlying funds”). The Fund invests primarily in funds managed by Amundi Asset Management US, Inc. The Fund may also invest in securities of unaffiliated mutual funds or exchange-traded funds (“ETFs”). The Fund indirectly pays a portion of the expenses incurred by underlying funds. Consequently, an investment in the Fund entails more direct and indirect expenses than direct investment in the applicable underlying funds.

The Fund offers five classes of shares designated as Class A, Class C, Class K, Class R and Class Y shares. Class K shares had not commenced operations as of July 31, 2021. Each class of shares represents an interest in the same portfolio of investments of the Fund and has identical rights (based on relative net asset values) to assets and liquidation proceeds. Share classes can bear different rates of class-specific fees and expenses such as transfer agent and distribution fees. Differences in class-specific fees and expenses will result in differences in net investment income and, therefore, the payment of different dividends from net investment income earned by each class. The Amended and Restated Declaration of Trust of the Trust gives the Board of Trustees the flexibility to specify either per-share voting or dollar-weighted voting when submitting matters for shareowner approval. Under per-share voting, each share of a class of the Fund is entitled to one vote. Under dollar-weighted voting, a shareowner’s voting power is determined not by the number of shares owned, but by the dollar value of the shares on the record date. Each share class has exclusive voting rights with respect to matters affecting only that class, including with respect to the distribution plan for that class. There is no distribution plan for Class Y shares.

Amundi Asset Management US, Inc., an indirect wholly owned subsidiary of Amundi and Amundi’s wholly owned subsidiary, Amundi USA, Inc., serves as the Fund’s investment adviser (the “Adviser”). Amundi Distributor US, Inc., an affiliate of the Adviser, serves as the Fund’s distributor (the “Distributor”).

32 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update 2018-13 “Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement” (“ASU 2018-13”) which modifies disclosure requirements for fair value measurements, principally for Level 3 securities and transfers between levels of the fair value hierarchy. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. The Fund has adopted ASU 2018-13 for the year ended July 31, 2021. The impact to the Fund’s adoption was limited to changes in the Fund’s disclosures regarding fair value, primarily those disclosures related to transfers between levels of the fair value hierarchy and disclosure of the range and weighted average used to develop significant unobservable inputs for Level 3 fair value investments, when applicable.

The Fund is an investment company and follows investment company accounting and reporting guidance under U.S. GAAP. U.S. GAAP requires the management of the Fund to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income, expenses and gain or loss on investments during the reporting period. Actual results could differ from those estimates.

The following is a summary of significant accounting policies followed by the Fund in the preparation of its financial statements:

A. Security Valuation

The net asset value of the Fund is computed once daily, on each day the New York Stock Exchange (“NYSE”) is open, as of the close of regular trading on the NYSE.

Shares of open-end registered investment companies (including exchange-traded funds and money market mutual funds) are valued at such funds’ net asset value.

Shares of exchange-listed closed-end funds are valued by using the last sale price on the principal exchange where they are traded. Shares of closed-end interval funds that offer their shares at net asset value, are valued at such funds’ net asset value.

Securities for which independent pricing services or broker-dealers are unable to supply prices or for which market prices and/or quotations are not readily available or are considered to be unreliable are valued by a fair valuation team comprised of certain personnel of the Adviser pursuant to procedures adopted by the Fund’s Board of Trustees. The Adviser’s fair valuation team uses fair value methods approved by the Valuation Committee of the Board of Trustees. The Adviser’s fair valuation team is

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 33

responsible for monitoring developments that may impact fair valued securities and for discussing and assessing fair values on an ongoing basis, and at least quarterly, with the Valuation Committee of the Board of Trustees.

Inputs used when applying fair value methods to value a security may include credit ratings, the financial condition of the company, current market conditions and comparable securities. The Fund may use fair value methods if it is determined that a significant event has occurred after the close of the exchange or market on which the security trades and prior to the determination of the Fund’s net asset value. Examples of a significant event might include political or economic news, corporate restructurings, natural disasters, terrorist activity or trading halts. Thus, the valuation of the Fund’s securities may differ significantly from exchange prices, and such differences could be material.

At July 31, 2021, no securities were valued using fair value methods (other than securities valued using prices supplied by independent pricing services, broker-dealers or using a third party insurance industry pricing model).

B. Investment Income and Transactions

Dividend income is recorded on the ex-dividend date, except that certain dividends from foreign securities where the ex-dividend date may have passed are recorded as soon as the Fund becomes aware of the ex-dividend data in the exercise of reasonable diligence.

Interest income, including interest on income-bearing cash accounts, is recorded on the accrual basis. Dividend and interest income are reported net of unrecoverable foreign taxes withheld at the applicable country rates and net of income accrued on defaulted securities.

Interest and dividend income payable by delivery of additional shares is reclassified as PIK (payment-in-kind) income upon receipt and is included in interest and dividend income, respectively.

Security transactions are recorded as of trade date. Gains and losses on sales of investments are calculated on the identified cost method for both financial reporting and federal income tax purposes.

C. Foreign Currency Translation

The books and records of the Fund are maintained in U.S. dollars. Amounts denominated in foreign currencies are translated into U.S. dollars using current exchange rates.

Net realized gains and losses on foreign currency transactions, if any, represent, among other things, the net realized gains and losses on foreign currency contracts, disposition of foreign currencies and the difference between the amount of income accrued and the U.S. dollars actually

34 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

received. Further, the effects of changes in foreign currency exchange rates on investments are not segregated on the Statement of Operations from the effects of changes in the market prices of those securities, but are included with the net realized and unrealized gain or loss on investments.

D. Federal Income Taxes

It is the Fund’s policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute all of its net taxable income and net realized capital gains, if any, to its shareowners. Therefore, no provision for federal income taxes is required. As of July 31, 2021, the Fund did not accrue any interest or penalties with respect to uncertain tax positions, which, if applicable, would be recorded as an income tax expense on the Statement of Operations. Tax returns filed within the prior three fiscal years remain subject to examination by federal and state tax authorities.

The amount and character of income and capital gain distributions to shareowners are determined in accordance with federal income tax rules, which may differ from U.S. GAAP. Distributions in excess of net investment income or net realized gains are temporary over distributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes. Capital accounts within the financial statements are adjusted for permanent book/tax differences to reflect tax character, but are not adjusted for temporary differences.

The tax character of distributions paid during the years ended July 31, 2021 and July 31, 2020, were as follows:

	2021	2020
Distributions paid from:
Ordinary income	$ 9,730,229	$12,787,400
Long-term capital gains	1,781,673	13,331,725
Total	$11,511,902	$26,119,125

The following shows the components of distributable earnings on a federal income tax basis at July 31, 2021:

	2021
Distributable earnings:
Undistributed ordinary income	$ 5,666,926
Undistributed long-term capital gains	7,096,139
Unrealized appreciation/(depreciation)	69,148,407
Total	$81,911,472

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 35

The differences between book-basis and tax-basis net unrealized appreciation/(depreciation) are attributable to the tax deferral of losses on wash sales.

E. Fund Shares

The Fund records sales and repurchases of its shares as of trade date. The Distributor earned $42,710 in underwriting commissions on the sale of Class A shares during the year ended July 31, 2021.

F. Class Allocations

Income, common expenses and realized and unrealized gains and losses are calculated at the Fund level and allocated daily to each class of shares based on its respective percentage of adjusted net assets at the beginning of the day.

Distribution fees are calculated based on the average daily net asset value attributable to Class A, Class C and Class R shares of the Fund, respectively (see Note 5). Class Y shares do not pay distribution fees. All expenses and fees paid to the Fund’s transfer agent for its services are allocated among the classes of shares based on the number of accounts in each class and the ratable allocation of related out-of-pocket expenses (see Note 4).

Distributions to shareowners are recorded as of the ex-dividend date. Distributions paid by the Fund with respect to each class of shares are calculated in the same manner and at the same time, except that net investment income dividends to Class A, Class C, Class R and Class Y shares can reflect different transfer agent and distribution expense rates.

G. Risks

The value of securities held by the Fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political or regulatory conditions, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past several years, financial markets have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. These conditions may continue, recur, worsen or spread. A general rise in interest rates could adversely affect the price and liquidity of fixed-income securities and could also result in increased redemptions from the Fund.

Some of the underlying funds can invest in either high yield securities or small/emerging growth companies. Investments in these types of securities generally are subject to greater volatility than either higher-grade securities or more established companies in more developed markets, respectively.

36 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

The Fund may gain exposure to insurance-linked securities by investing in a closed-end interval fund, Pioneer ILS Interval Fund, an affiliate of the Adviser. The Fund’s investment in Pioneer ILS Interval Fund at July 31, 2021 is listed in the Schedule of Investments.

With the increased use of technologies such as the Internet to conduct business, the Fund is susceptible to operational, information security and related risks. While the Fund’s Adviser has established business continuity plans in the event of, and risk management systems to prevent, limit or mitigate, such cyber-attacks, there are inherent limitations in such plans and systems including the possibility that certain risks have not been identified. Furthermore, the Fund cannot control the cybersecurity plans and systems put in place by service providers to the Fund such as Brown Brothers Harriman & Co., the Fund’s custodian and accounting agent, and DST Asset Manager Solutions, Inc., the Fund’s transfer agent. In addition, many beneficial owners of Fund shares hold them through accounts at broker-dealers, retirement platforms and other financial market participants over which neither the Fund nor the Adviser exercises control. Each of these may in turn rely on service providers to them, which are also subject to the risk of cyber-attacks. Cybersecurity failures or breaches at the Adviser or the Fund’s service providers or intermediaries have the ability to cause disruptions and impact business operations, potentially resulting in financial losses, interference with the Fund’s ability to calculate its net asset value, impediments to trading, the inability of Fund shareowners to effect share purchases, redemptions or exchanges or receive distributions, loss of or unauthorized access to private shareowners information and violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, or additional compliance costs. Such costs and losses may not be covered under any insurance. In addition, maintaining vigilance against cyber-attacks may involve substantial costs over time, and system enhancements may themselves be subject to cyber-attacks.

COVID-19

The respiratory illness COVID-19 caused by a novel coronavirus has resulted in a global pandemic and major disruption to economies and markets around the world, including the United States. Global financial markets have experienced extreme volatility and severe losses, and trading in many instruments has been disrupted. Liquidity for many instruments has been greatly reduced for periods of time. Some interest rates are very low and in some cases yields are negative. Some sectors of the economy and individual issuers have experienced particularly large losses. These circumstances may continue for an extended period of time, and may continue to affect

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 37

adversely the value and liquidity of the Fund’s investments. The ultimate economic fallout from the pandemic, and the long-term impact on economies, markets, industries and individual issuers, are not known. Governments and central banks, including the Federal Reserve in the U.S., have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The impact of these measures will not be known for some time. The consequences of high public debt, including its future impact on the economy and securities markets, likewise may not be known for some time.

The Fund’s prospectus contains unaudited information regarding the Fund’s principal risks. Please refer to that document when considering the Fund’s principal risks.

2. Management Agreement

The Adviser manages the Fund’s portfolio. The Fund does not pay a direct management fee to the Adviser. The Fund bears a pro rata portion of the fees and expenses, including management fees, of each underlying fund in which the Fund invests. The Fund invests primarily in funds managed by the Adviser.

In addition, under the management and administration agreements, certain other services and costs, including accounting, regulatory reporting and insurance premiums, are paid by the Fund as administrative reimbursements. Included in “Due to affiliates” reflected on the Statement of Assets and Liabilities is $0 payable to the Adviser at July 31, 2021.

The Adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than extraordinary expenses, such as litigation, taxes, brokerage commissions and acquired fund fees and expenses) of the Fund to the extent required to reduce fund expenses to 0.70%, 1.45% and 0.78% of the average daily net assets attributable to Class A, Class C and Class R shares, respectively. These expense limitations are in effect through December 1, 2021. There can be no assurance that the Adviser, will extend the expense limitation agreement for a class of shares beyond the date referred to above.

3. Compensation of Trustees and Officers

The Fund pays an annual fee to its Trustees. The Adviser reimburses the Fund for fees paid to the Interested Trustees. The Fund does not pay any salary or other compensation to its officers. For the year ended July 31, 2021, the Fund paid $15,873 in Trustees’ compensation, which is reflected on the Statement of Operations as Trustees’ fees. At July 31, 2021, the Fund had a payable for Trustees’ fees on its Statement of Assets and Liabilities of $1,218.

38 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

4. Transfer Agent

DST Asset Manager Solutions, Inc. serves as the transfer agent to the Fund at negotiated rates. Transfer agent fees and payables shown on the Statement of Operations and the Statement of Assets and Liabilities, respectively, include sub-transfer agent expenses incurred through the Fund’s omnibus relationship contracts.

In addition, the Fund reimbursed the transfer agent for out-of-pocket expenses incurred by the transfer agent related to shareowner communications activities such as proxy and statement mailings, and outgoing phone calls. For the year ended July 31, 2021, such out-of-pocket expenses by class of shares were as follows:


Shareowner Communications:
Class A	$116,394
Class C	12,702
Class R	191
Class Y	591
Total	$129,878

5. Distribution and Service Plans

The Fund has adopted a distribution plan (the “Plan”) pursuant to Rule 12b-1 of the Investment Company Act of 1940 with respect to its Class A, Class C and Class R shares. Pursuant to the Plan, the Fund pays the Distributor 0.25% of the Fund’s average daily net assets attributable to Class A shares as compensation for personal services and/or account maintenance services or distribution services with regard to Class A shares. Pursuant to the Plan, the Fund also pays the Distributor 1.00% of the average daily net assets attributable to Class C shares. The fee for Class C shares consists of a 0.25% service fee and a 0.75% distribution fee paid as compensation for personal services and/or account maintenance services or distribution services with regard to Class C shares. Pursuant to the Plan, the Fund further pays the Distributor 0.50% of the average daily net assets attributable to Class R shares for distribution services. Included in “Due to affiliates” reflected on the Statement of Assets and Liabilities is $11,727 in distribution fees payable to the Distributor at July 31, 2021.

The Fund also has adopted a separate service plan for Class R shares (the “Service Plan”). The Service Plan authorizes the Fund to pay securities dealers, plan administrators or other service organizations that agree to provide certain services to retirement plans or plan participants holding shares of the Fund a service fee of up to 0.25% of the Fund’s average daily net assets attributable to Class R shares held by such plans.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 39

In addition, redemptions of Class A and Class C shares may be subject to a contingent deferred sales charge (“CDSC”). A CDSC of 1.00% may be imposed on redemptions of certain net asset value purchases of Class A shares within 12 months of purchase. Redemptions of Class C shares within 12 months of purchase are subject to a CDSC of 1.00%, based on the lower of cost or market value of shares being redeemed. Shares purchased as part of an exchange remain subject to any CDSC that applied to the original purchase of those shares. There is no CDSC for Class R or Class Y shares. Proceeds from the CDSCs are paid to the Distributor. For the year ended July 31, 2021, CDSCs in the amount of $5,659 were paid to the Distributor.

6. Transactions in Underlying Funds

An affiliated issuer is a company in which the Fund has a direct or indirect ownership of, control of, or voting power of 5 percent or more of the outstanding voting shares, or a company which is under common ownership control. At July 31, 2021, the value of the Fund’s investment in affiliated issuers was $454,888,526, which represents 99.2% of the Fund’s net assets. Transactions in affiliated issuers by the Fund for the year ended July 31, 2021 were as follows:

40 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21


						Change in
				Net		net unrealized
				realized		appreciation/
				gain/(loss)	Dividends	(depreciation)
				from	from	from	Shares
Name of	Value at			Investments	Investment	Investments	held at	Value
the Affiliated	July 31,			in Affiliated	in Affiliated	in Affiliated	July 31,	July 31,
Issuers	2020	Purchases	Sales	Issuers	Issuers	Issuers	2021	2021
Pioneer Bond
Fund Class K	$ 1,141,019	$28,044,905 $ (29,535,114) $ 282,179			$ 213,223	$ (86,381)	5,866	$ 59,831
Pioneer Core
Equity Fund
Class K	14,434,981	1,193,985	(6,596,307)	650,302	142,880	2,400,624	464,002	12,226,465
Pioneer Corporate
High Yield Fund
Class Y	4,831,425	—	(5,101,118)	—	20,557	249,136	—	—
Pioneer Corporate
High Yield Fund
Class Y	—	5,092,750	(5,266,623)	3,525	170,348	—	—	—
Pioneer Equity
Income Fund
Class K	9,954,619	1,217,674	(2,670,298)	129,843	198,521	2,884,218	282,279	11,714,577
Pioneer Flexible
Opportunities Fund
Class K	79,856,684	98,720	(7,614,989)	(134,837)	944,510	18,218,328	6,411,819	91,368,416
Pioneer Fund
Class K	14,384,960	862,892	(12,631,919)	1,742,518	13,456	463,653	115,628	4,835,560
Pioneer
Fundamental
Growth Fund
Class K	10,260,154	—	(6,563,522)	1,387,456	17,115	(105,932)	138,835	4,995,271
Pioneer Global
Equity Fund
Class K	51,244,710	345,233	(3,603,118)	831,633	758,947	18,528,856	3,306,129	68,106,261
Pioneer ILS
Interval Fund	—	11,400,001	—	—	—	255,728	1,345,927	11,655,729
Pioneer
International
Equity Fund
Class Y	48,959,698	—	(3,127,611)	658,111	328,801	14,269,086	2,199,787	61,088,085
Pioneer Multi-Asset
Income Fund
Class K	119,332,363	2,532,555	(9,837,578)	(641,054)	6,878,581	18,348,939	11,365,541	136,613,806
Pioneer Multi-Asset
Ultrashort Income
Fund Class K	19,841,369	48,087,329	(18,688,692)	(302,838)	351,594	573,395	5,119,318	49,862,157
Pioneer Strategic
Income Fund
Class K	20,009,995	76,509	(18,986,176)	1,794,837	514,614	(1,047,411)	206,140	2,362,368
Total	$394,251,977	$98,952,553 $(130,223,065) $6,401,675			$10,553,147	$ 74,952,239		$454,888,526

Annual and semi-annual reports for the Pioneer funds are available on the funds’ web page(s) at www.amundi.com/us

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 41

Report of Independent Registered Public Accounting Firm

To the Board of Trustees of Pioneer Asset Allocation Trust and the Shareholders of Pioneer Solutions – Balanced Fund:

Opinion on the Financial Statements

We have audited the accompanying statement of assets and liabilities of Pioneer Solutions – Balanced Fund (the “Fund”) (one of the funds constituting Pioneer Asset Allocation Trust (the “Trust”)), including the schedule of investments, as of July 31, 2021, and the related statement of operations for the year then ended, the statements of changes in net assets for each of the two years in the period then ended, the financial highlights for each of the five years in the period then ended and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of Pioneer Solutions – Balanced Fund at July 31, 2021, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended, and its financial highlights for each of the five years in the period then ended, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Trust’s management. Our responsibility is to express an opinion on the Fund’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Fund in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Trust is not required to have, nor were we engaged to perform, an audit of the Trust’s internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting, but not for the purpose of expressing an opinion on the effectiveness of the Trust’s internal control over financial reporting. Accordingly, we express no such opinion.

42 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our procedures included confirmation of securities owned as of July 31, 2021, by correspondence with the custodian and brokers or by other appropriate auditing procedures where replies from brokers were not received. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

We have served as the auditor of one or more investment companies in the Pioneer family of funds since 2017.

Boston, Massachusetts
September 28, 2021

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 43

Statement Regarding Liquidity Risk Management Program

As required by law, the Fund has adopted and implemented a liquidity risk management program (the “Program”) that is designed to assess and manage liquidity risk. Liquidity risk is the risk that the Fund could not meet requests to redeem its shares without significant dilution of remaining investors’ interests in the Fund. The Fund’s Board of Trustees designated a liquidity risk management committee (the “Committee”) consisting of employees of Amundi Asset Management US, Inc. (the “Adviser”) to administer the Program.

The Committee provided the Board of Trustees with a report that addressed the operation of the Program and assessed its adequacy and effectiveness of implementation (the “Report”). The Report covered the period from January 1, 2020 through December 31, 2020 (the “Reporting Period”).

The Report confirmed that, throughout the Reporting Period, the Committee had monitored the Fund’s portfolio liquidity and liquidity risk on an ongoing basis, as described in the Program and in Board reporting throughout the Reporting Period.

The Report discussed the Committee’s annual review of the Program, which addressed, among other things, the following elements of the Program:

The Committee reviewed the Fund’s investment strategy and liquidity of portfolio investments during both normal and reasonably foreseeable stressed conditions. The Committee noted that the Fund’s investment strategy continues to be appropriate for an open-end fund, taking into account, among other things, whether and to what extent the Fund held less liquid and illiquid assets and the extent to which any such investments affected the Fund’s ability to meet redemption requests. In managing and reviewing the Fund’s liquidity risk, the Committee also considered the extent to which the Fund’s investment strategy involves a relatively concentrated portfolio or large positions in particular issuers, the extent to which the Fund uses borrowing for investment purposes, and the extent to which the Fund uses derivatives (including for hedging purposes). The Committee also reviewed the Fund’s short-term and long-term cash flow projections during both normal and reasonably foreseeable stressed conditions. In assessing the Fund’s cash flow projections, the Committee considered, among other factors, historical net redemption activity, redemption policies, ownership concentration, distribution channels, and the degree of certainty associated with the Fund’s short-term and long-term cash flow projections. The Committee also considered the Fund’s holdings of cash and cash equivalents, as well as borrowing arrangements

44 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

and other funding sources, including, if applicable, the Fund’s participation in a credit facility, as components of the Fund’s ability to meet redemption requests. The Fund has adopted an in-kind redemption policy which may be utilized to meet larger redemption requests.

The Committee reviewed the Program’s liquidity classification methodology for categorizing the Fund’s investments into one of four liquidity buckets. In reviewing the Fund’s investments, the Committee considered, among other factors, whether trading varying portions of a position in a particular portfolio investment or asset class in sizes the Fund would reasonably anticipate trading, would be reasonably expected to significantly affect liquidity.

The Committee performed an analysis to determine whether the Fund is required to maintain a Highly Liquid Investment Minimum, and determined that no such minimum is required because the Fund primarily holds highly liquid investments.

The Report stated that the Committee concluded the Program operates adequately and effectively, in all material respects, to assess and manage the Fund’s liquidity risk throughout the Reporting Period.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 45

Additional Information (unaudited)

For the year ended July 31, 2021, certain dividends paid by the Fund may be subject to a maximum tax rate of 20%. The Fund intends to designate up to the maximum amount of such dividends allowable, as taxed at a maximum rate of 20%. Complete information will be computed and reported in conjunction with our 2021 Form 1099-DIV.

The qualifying percentage of the Fund's ordinary income dividends for the purpose of the corporate dividends received deduction was 28.44%.

46 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

Trustees, Officers and Service Providers

Investment Adviser and Administrator

Amundi Asset Management US, Inc.

Custodian and Sub-Administrator

Brown Brothers Harriman & Co.

Independent Registered Public Accounting Firm

Ernst & Young LLP

Principal Underwriter

Amundi Distributor US, Inc.

Legal Counsel

Morgan, Lewis & Bockius LLP

Transfer Agent

DST Asset Manager Solutions, Inc.

Proxy Voting Policies and Procedures of the Fund are available without charge, upon request, by calling our toll free number (1-800-225-6292). Information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30 is publicly available to shareowners at www.amundi.com/us. This information is also available on the Securities and Exchange Commission’s web site at www.sec.gov.

Trustees and Officers

The Fund’s Trustees and officers are listed below, together with their principal occupations and other directorships they have held during at least the past five years. Trustees who are interested persons of the Fund within the meaning of the 1940 Act are referred to as Interested Trustees. Trustees who are not interested persons of the Fund are referred to as Independent Trustees. Each of the Trustees serves as a Trustee of each of the 45 U.S. registered investment portfolios for which Amundi US serves as investment adviser (the “Pioneer Funds”). The address for all Trustees and all officers of the Fund is 60 State Street, Boston, Massachusetts 02109.

The Statement of Additional Information of the Fund includes additional information about the Trustees and is available, without charge, upon request, by calling 1-800-225-6292.

Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21 47

Independent Trustees


Name, Age and Position	Term of Office and	Principal Occupation(s) During At Least	Other Directorships Held by Trustee
Held With the Fund	Length of Service	The Past Five Years	During At Least The Past Five Years
Thomas J. Perna (70)	Trustee since 2006.	Private investor (2004 – 2008 and 2013 – present); Chairman	Director, Broadridge Financial
Chairman of the Board	Serves until a successor	(2008 – 2013) and Chief Executive Officer (2008 – 2012), Quadriserv, Inc.	Solutions, Inc. (investor
and Trustee	trustee is elected or	(technology products for securities lending industry); and Senior	communications and securities
	earlier retirement	Executive Vice President, The Bank of New York (financial and securities	processing provider for financial
	or removal.	services) (1986 – 2004)	services industry) (2009 – present);
			Director, Quadriserv, Inc. (2005 –
			2013); and Commissioner, New
			Jersey State Civil Service
			Commission (2011 – 2015)
John E. Baumgardner,	Trustee since 2019.	Of Counsel (2019 – present), Partner (1983-2018), Sullivan & Cromwell	Chairman, The Lakeville Journal
Jr. (70)	Serves until a successor	LLP (law firm).	Company, LLC, (privately-held
Trustee	trustee is elected or		community newspaper group)
	earlier retirement		(2015-present)
	or removal.
Diane Durnin (64)	Trustee since 2019.	Managing Director - Head of Product Strategy and Development, BNY	None
Trustee	Serves until a successor	Mellon Investment Management (investment management firm)
	trustee is elected or	(2012-2018); Vice Chairman – The Dreyfus Corporation (2005 – 2018):
	earlier retirement	Executive Vice President Head of Product, BNY Mellon Investment
	or removal.	Management (2007-2012); Executive Director- Product Strategy, Mellon
		Asset Management (2005-2007); Executive Vice President Head of Products,
		Marketing and Client Service, Dreyfus Corporation (investment management
		firm) (2000-2005); and Senior Vice President Strategic Product and Business
		Development, Dreyfus Corporation (1994-2000)

48 Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21


Name, Age and Position	Term of Office and	Principal Occupation(s) During At Least	Other Directorships Held by Trustee
Held With the Fund	Length of Service	The Past Five Years	During At Least The Past Five Years
Benjamin M. Friedman (76)	Trustee since 2008.	William Joseph Maier Professor of Political Economy, Harvard	Trustee, Mellon Institutional Funds
Trustee	Serves until a successor	University (1972 – present)	Investment Trust and Mellon
	trustee is elected or		Institutional Funds Master Portfolio
	earlier retirement		(oversaw 17 portfolios in fund
	or removal.		complex) (1989 - 2008)
Craig C. MacKay (58)	Trustee since 2021.	Partner, England & Company, LLC (advisory firm) (2012 – present); Group	Board Member of Carver Bancorp,
Trustee	Serves until a successor	Head – Leveraged Finance Distribution, Oppenheimer & Company	Inc. (holding company) and Carver
	trustee is elected or	(investment bank) (2006 – 2012); Group Head – Private Finance & High	Federal Savings Bank, NA (2017 –
	earlier retirement	Yield Capital Markets Origination, SunTrust Robinson Humphrey	present); Advisory Council Member,
	or removal.	(investment bank) (2003 – 2006); and Founder and Chief Executive	MasterShares ETF (2016 – 2017);
		Officer, HNY Associates, LLC (investment bank) (1996 – 2003)	Advisory Council Member, The Deal
			(financial market information
			publisher) (2015 – 2016); Board Co-
			Chairman and Chief Executive
			Officer, Danis Transportation
			Company (privately-owned
			commercial carrier) (2000 – 2003);
			Board Member and Chief Financial
			Officer, Customer Access Resources
			(privately-owned teleservices
			company) (1998 – 2000); Board
			Member, Federation of Protestant
			Welfare Agencies (human services
			agency) (1993 – present); and
			Board Treasurer, Harlem Dowling
			Westside Center (foster care
			agency) (1999 – 2018)

Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21 49

Independent Trustees (continued)


Name, Age and Position	Term of Office and	Principal Occupation(s) During At Least	Other Directorships Held by Trustee
Held With the Fund	Length of Service	The Past Five Years	During At Least The Past Five Years
Lorraine H. Monchak (65)	Trustee since 2017.	Chief Investment Officer, 1199 SEIU Funds (healthcare workers union	None
Trustee	(Advisory Trustee from	pension funds) (2001 – present); Vice President – International
	2014 - 2017). Serves	Investments Group, American International Group, Inc. (insurance company)
	until a successor trustee	(1993 – 2001); Vice President – Corporate Finance and Treasury Group,
	is elected or earlier	Citibank, N.A. (1980 – 1986 and 1990 – 1993); Vice President – Asset/Liability
	retirement or removal.	Management Group, Federal Farm Funding Corporation (government-
		sponsored issuer of debt securities) (1988 – 1990); Mortgage Strategies
		Group, Shearson Lehman Hutton, Inc. (investment bank) (1987 – 1988); and
		Mortgage Strategies Group, Drexel Burnham Lambert, Ltd. (investment
		bank) (1986 – 1987)
Marguerite A. Piret (73)	Trustee since 2005.	Chief Financial Officer, American Ag Energy, Inc. (controlled environment	Director of New America High
Trustee	Serves until a successor	and agriculture company) (2016 – present); and President and Chief	Income Fund, Inc. (closed-end
	trustee is elected or	Executive Officer, Metric Financial Inc. (formerly known as Newbury Piret	investment company) (2004 –
	earlier retirement	Company) (investment banking firm) (1981 – 2019)	present); and Member, Board of
	or removal.		Governors, Investment Company
			Institute (2000 – 2006)
Fred J. Ricciardi (74)	Trustee since 2014.	Private investor (2020 – present); Consultant (investment company	None
Trustee	Serves until a successor	services) (2012 – 2020); Executive Vice President, BNY Mellon (financial and
	trustee is elected or	investment company services) (1969 – 2012); Director, BNY International
	earlier retirement	Financing Corp. (financial services) (2002 – 2012); Director, Mellon Overseas
	or removal.	Investment Corp. (financial services) (2009 – 2012); Director, Financial Models
		(technology) (2005-2007); Director, BNY Hamilton Funds, Ireland (offshore
		investment companies) (2004-2007); Chairman/Director, AIB/BNY Securities
		Services, Ltd., Ireland (financial services) (1999-2006); and Chairman, BNY
		Alternative Investment Services, Inc. (financial services) (2005-2007)

50 Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21

Interested Trustees


Name, Age and Position	Term of Office and	Principal Occupation(s) During At Least	Other Directorships Held by Trustee
Held With the Fund	Length of Service	The Past Five Years	During At Least The Past Five Years
Lisa M. Jones (59)*	Trustee since 2017.	Director, CEO and President of Amundi US, Inc. (investment	None
Trustee, President and	Serves until a successor	management firm) (since September 2014); Director, CEO and President
Chief Executive Officer	trustee is elected or	of Amundi Asset Management US, Inc. (since September 2014); Director,
	earlier retirement	CEO and President of Amundi Distributor US, Inc. (since September 2014);
	or removal	Director, CEO and President of Amundi Asset Management US, Inc. (since
		September 2014); Chair, Amundi US, Inc., Amundi Distributor US, Inc. and
		Amundi Asset Management US, Inc. (September 2014 – 2018); Managing
		Director, Morgan Stanley Investment Management (investment management
		firm) (2010 – 2013); Director of Institutional Business, CEO of International,
		Eaton Vance Management (investment management firm) (2005 – 2010);
		and Director of Amundi Holdings US, Inc. (since 2017)

Kenneth J. Taubes (63)*	Trustee since 2014.	Director and Executive Vice President (since 2008) and Chief Investment	None
Trustee	Serves until a successor	Officer, U.S. (since 2010) of Amundi US, Inc. (investment management firm);
	trustee is elected or	Director and Executive Vice President and Chief Investment Officer, U.S. of
	earlier retirement	Amundi US (since 2008); Executive Vice President and Chief Investment
	or removal	Officer, U.S. of Amundi Asset Management US, Inc. (since 2009); Portfolio
		Manager of Amundi US (since 1999); and Director of Amundi Holdings
		US, Inc. (since 2017)

* Ms. Jones and Mr. Taubes are Interested Trustees because they are officers or directors of the Fund’s investment adviser and certain of its affiliates.

Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21 51

Fund Officers


Name, Age and Position	Term of Office and	Principal Occupation(s) During At Least	Other Directorships Held by Officer
Held With the Fund	Length of Service	The Past Five Years	During At Least The Past Five Years
Christopher J. Kelley (56)	Since 2005. Serves	Vice President and Associate General Counsel of Amundi US since	None
Secretary and Chief	at the discretion of	January 2008; Secretary and Chief Legal Officer of all of the Pioneer Funds
Legal Officer	the Board	since June 2010; Assistant Secretary of all of the Pioneer Funds from
		September 2003 to May 2010; and Vice President and Senior Counsel of
		Amundi US from July 2002 to December 2007
Thomas Reyes (58)	Since 2010. Serves	Assistant General Counsel of Amundi US since May 2013 and Assistant	None
Assistant Secretary	at the discretion of	Secretary of all the Pioneer Funds since June 2010; and Counsel of
	the Board	Amundi US from June 2007 to May 2013
Anthony J. Koenig, Jr. (57)	Since 2021. Serves	Senior Vice President – Fund Treasury of Amundi US; Treasurer of all of	None
Treasurer and Chief Financial	at the discretion of	the Pioneer Funds since May 2021; Assistant Treasurer of all of the Pioneer
and Accounting Officer	the Board	Funds from January 2021 to May 2021; and Chief of Staff, US Investment
		Management of Amundi US from May 2008 to January 2021
Luis I. Presutti (56)	Since 2005. Serves	Director – Fund Treasury of Amundi US since 1999; and Assistant	None
Assistant Treasurer	at the discretion of	Treasurer of all of the Pioneer Funds since 1999
	the Board
Gary Sullivan (63)	Since 2005. Serves	Senior Manager – Fund Treasury of Amundi US since 2012; and Assistant	None
Assistant Treasurer	at the discretion of	Treasurer of all of the Pioneer Funds since 2002
	the Board
Antonio Furtado (39)	Since 2020. Serves	Fund Oversight Manager – Fund Treasury of Amundi US since 2020;	None
Assistant Treasurer	at the discretion of	Assistant Treasurer of all of the Pioneer Funds since 2020; and Senior Fund
	the Board	Treasury Analyst from 2012 - 2020

52 Pioneer Solutions –Balanced Fund | Annual Report | 7/31/21


Name, Age and Position	Term of Office and	Principal Occupation(s) During At Least	Other Directorships Held by Officer
Held With the Fund	Length of Service	The Past Five Years	During At Least The Past Five Years
Michael Melnick (50)	Since July 2021. Serves	Vice President - Deputy Fund Treasurer of Amundi US since May 2021;	None
Assistant Treasurer	at the discretion of	Assistant Treasurer of all of the Pioneer Funds since July 2021; Director of
	the Board	Regulatory Reporting of Amundi US from 2001 – 2021; and Director of
		Tax of Amundi US from 2000 - 2001
John Malone (50)	Since 2008. Serves	Managing Director, Chief Compliance Officer of Amundi US Asset	None
Chief Compliance Officer	at the discretion of	Management; Amundi Asset Management US, Inc.; and the Pioneer Funds
	the Board	since September 2018; and Chief Compliance Officer of Amundi
		Distributor US, Inc. since January 2014.
Kelly O’Donnell (50)	Since 2006. Serves	Vice President – Amundi Asset Management; and Anti-Money Laundering	None
Anti-Money Laundering	at the discretion of	Officer of all the Pioneer Funds since 2006
Officer	the Board

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60 Pioneer Solutions – Balanced Fund | Annual Report | 7/31/21

How to Contact Amundi

We are pleased to offer a variety of convenient ways for you to contact us for assistance or information.

Call us for:
Account Information, including existing accounts,
new accounts, prospectuses, applications
and service forms	1-800-225-6292
FactFone^SMfor automated fund yields, prices,
account information and transactions	1-800-225-4321
Retirement plans information	1-800-622-0176

Write to us:

Amundi

P.O. Box 219427

Kansas City, MO 64121-9427


Our toll-free fax	1-800-225-4240

Our internet e-mail address	us.askamundi@amundi.com
(for general questions about Amundi only)

Visit our web site: www.amundi.com/us

This report must be preceded or accompanied by a prospectus.

The Fund files a complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year as an exhibit to its reports on Form N-PORT. Shareholders may view the filed Form N-PORT by visiting the Commission’s web site at https://www.sec.gov.

Amundi Asset Management US, Inc.
60 State Street
Boston, MA 02109
www.amundi.com/us

Securities offered through Amundi Distributor US, Inc.,
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
© 2021 Amundi Asset Management US, Inc. 19417-15-0921

ITEM 2. CODE OF ETHICS.

(a) Disclose whether, as of the end of the period covered by the report, the registrant has adopted a code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party. If the registrant has not adopted such a code of ethics, explain why it has not done so.

The registrant has adopted, as of the end of the period covered by this report, a code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer and controller.

(b) For purposes of this Item, the term “code of ethics” means written standards that are reasonably designed to deter wrongdoing and to promote:

(1) Honest and ethical conduct, including the ethical handling of actual or apparent conflicts of interest between personal and professional relationships;

(2) Full, fair, accurate, timely, and understandable disclosure in reports and documents that a registrant files with, or submits to, the Commission and in other public communications made by the registrant;

(3) Compliance with applicable governmental laws, rules, and regulations;

(4) The prompt internal reporting of violations of the code to an appropriate person or persons identified in the code; and

(5) Accountability for adherence to the code.

(c) The registrant must briefly describe the nature of any amendment, during the period covered by the report, to a provision of its code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party, and that relates to any element of the code of ethics definition enumerated in paragraph (b) of this Item. The registrant must file a copy of any such amendment as an exhibit pursuant to Item 10(a), unless the registrant has elected to satisfy paragraph (f) of this Item by posting its code of ethics on its website pursuant to paragraph (f)(2) of this Item, or by undertaking to provide its code of ethics to any person without charge, upon request, pursuant to paragraph (f)(3) of this Item.

The registrant has made no amendments to the code of ethics during the period covered by this report.

(d) If the registrant has, during the period covered by the report, granted a waiver, including an implicit waiver, from a provision of the code of ethics to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, regardless of whether these individuals are employed by the registrant or a third party, that relates to one or more of the items set forth in paragraph (b) of this Item, the registrant must briefly describe the nature of the waiver, the name of the person to whom the waiver was granted, and the date of the waiver.

Not applicable.

(e) If the registrant intends to satisfy the disclosure requirement under paragraph (c) or (d) of this Item regarding an amendment to, or a waiver from, a provision of its code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions and that relates to any element of the code of ethics definition

enumerated in paragraph (b) of this Item by posting such information on its Internet website, disclose the registrant’s Internet address and such intention.

Not applicable.

(f) The registrant must:

(1) File with the Commission, pursuant to Item 12(a)(1), a copy of its code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, as an exhibit to its annual report on this Form N-CSR (see attachment);

(2) Post the text of such code of ethics on its Internet website and disclose, in its most recent report on this Form N-CSR, its Internet address and the fact that it has posted such code of ethics on its Internet website; or

(3) Undertake in its most recent report on this Form N-CSR to provide to any person without charge, upon request, a copy of such code of ethics and explain the manner in which such request may be made. See Item 10(2)

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

(a) (1) Disclose that the registrant’s board of trustees has determined that the registrant either:

(i) Has at least one audit committee financial expert serving on its audit committee; or

(ii) Does not have an audit committee financial expert serving on its audit committee.

The registrant’s Board of Trustees has determined that the registrant has at least one audit committee financial expert.

(2) If the registrant provides the disclosure required by paragraph (a)(1)(i) of this Item, it must disclose the name of the audit committee financial expert and whether that person is “independent.” In order to be considered “independent” for purposes of this Item, a member of an audit committee may not, other than in his or her capacity as a member of the audit committee, the board of trustees, or any other board committee:

(i) Accept directly or indirectly any consulting, advisory, or other compensatory fee from the issuer; or

(ii) Be an “interested person” of the investment company as defined in Section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19)).

Mr. Fred J. Ricciardi, an independent trustee, is such an audit committee financial expert.

(3) If the registrant provides the disclosure required by paragraph (a)(1) (ii) of this Item, it must explain why it does not have an audit committee financial expert.

Not applicable.

ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

(a) Disclose, under the caption AUDIT FEES, the aggregate fees billed for each of the last two fiscal years for professional services rendered by the principal accountant for the audit of the registrant’s annual financial statements or services that are normally provided by the accountant in connection with statutory and regulatory filings or engagements for those fiscal years.

The audit fees for the Trust were $20,400 payable to Ernst & Young LLP for the year ended July 31, 2021 and $20,400 for the year ended July 31, 2020.

(b) Disclose, under the caption AUDIT-RELATED FEES, the aggregate fees billed in each of the last two fiscal years for assurance and related services by the principal accountant that are reasonably related to the performance of the audit of the registrant’s financial statements and are not reported under paragraph (a) of this Item. Registrants shall describe the nature of the services comprising the fees disclosed under this category.

There were no audit-related services in 2021 or 2020.

(c) Disclose, under the caption TAX FEES, the aggregate fees billed in each of the last two fiscal years for professional services rendered by the principal accountant for tax compliance, tax advice, and tax planning. Registrants shall describe the nature of the services comprising the fees disclosed under this category.

The Trust paid aggregate non-audit fees to Ernst & Young LLP for tax services of $8,189 and $8,189 during the fiscal years ended July 31, 2021 and 2020, respectively.

(d) Disclose, under the caption ALL OTHER FEES, the aggregate fees billed in each of the last two fiscal years for products and services provided by the principal accountant, other than the services reported in paragraphs (a) through (c) of this Item. Registrants shall describe the nature of the services comprising the fees disclosed under this category.

There were no other fees in 2021 or 2020.

(e) (1) Disclose the audit committee’s pre-approval policies and procedures described in paragraph (c)(7) of Rule 2-01 of Regulation S-X.

PIONEER FUNDS

APPROVAL OF AUDIT, AUDIT-RELATED, TAX AND OTHER SERVICES

PROVIDED BY THE INDEPENDENT AUDITOR

SECTION I - POLICY PURPOSE AND APPLICABILITY

The Pioneer Funds recognize the importance of maintaining the independence of their outside auditors. Maintaining independence is a shared responsibility involving Amundi Asset Management US, Inc., the audit committee and the independent auditors.

The Funds recognize that a Fund’s independent auditors: 1) possess knowledge of the Funds, 2) are able to incorporate certain services into the scope of the audit, thereby avoiding redundant work, cost and disruption of Fund personnel and processes, and 3) have expertise that has value to the Funds. As a result, there are situations where it is desirable to use the Fund’s independent auditors for services in addition to the annual audit and where the potential for conflicts of interests are minimal. Consequently, this policy, which is intended to comply with Rule 210.2-01(C)(7), sets forth guidelines and procedures to be followed by the Funds when retaining the independent audit firm to perform audit, audit-related tax and

other services under those circumstances, while also maintaining independence.

Approval of a service in accordance with this policy for a Fund shall also constitute approval for any other Fund whose pre-approval is required pursuant to Rule 210.2-01(c)(7)(ii).

In addition to the procedures set forth in this policy, any non-audit services that may be provided consistently with Rule 210.2-01 may be approved by the Audit Committee itself and any pre-approval that may be waived in accordance with Rule 210.2-01(c)(7)(i)(C) is hereby waived.

Selection of a Fund’s independent auditors and their compensation shall be determined by the Audit Committee and shall not be subject to this policy.


SECTION II - POLICY

SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION		SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES

I. AUDIT SERVICES	Services that are directly		o Accounting research assistance
	related to performing the		o SEC consultation, registration
	independent audit of the Funds		statements, and reporting
			o Tax accrual related matters
			o Implementation of new accounting standards
			o Compliance letters (e.g. rating agency letters)
			o Regulatory reviews and assistance
			regarding financial matters
			o Semi-annual reviews (if requested)
			o Comfort letters for closed end offerings
II. AUDIT-RELATED	Services which are not		o AICPA attest and agreed-upon procedures
SERVICES	prohibited under Rule		o Technology control assessments
	210.2-01(C)(4) (the “Rule”)		o Financial reporting control assessments
	and are related extensions of		o Enterprise security architecture
	the audit services support the		assessment
	audit, or use the knowledge/expertise
	gained from the audit procedures as a
	foundation to complete the project.
	In most cases, if the Audit-Related
	Services are not performed by the
	Audit firm, the scope of the Audit
	Services would likely increase.
	The Services are typically well-defined
	and governed by accounting
	professional standards (AICPA,
	SEC, etc.)

AUDIT COMMITTEE APPROVAL POLICY		AUDIT COMMITTEE REPORTING POLICY
o “One-time” pre-approval		o A summary of all such
for the audit period for all		services and related fees
pre-approved specific service		reported at each regularly
subcategories. Approval of the		scheduled Audit Committee
independent auditors as		meeting.
auditors for a Fund shall
constitute pre approval for
these services.

o “One-time” pre-approval		o A summary of all such
for the fund fiscal year within		services and related fees
a specified dollar limit		(including comparison to
for all pre-approved		specified dollar limits)
specific service subcategories		reported quarterly.

o Specific approval is
needed to exceed the
pre-approved dollar limit for
these services (see general
Audit Committee approval policy
below for details on obtaining
specific approvals)

o Specific approval is
needed to use the Fund’s
auditors for Audit-Related
Services not denoted as
“pre-approved”, or
to add a specific service
subcategory as “pre-approved”

SECTION III - POLICY DETAIL, CONTINUED


SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION	SPECIFIC PRE-APPROVED SERVICE
		SUBCATEGORIES
III. TAX SERVICES	Services which are not	o Tax planning and support
	prohibited by the Rule,	o Tax controversy assistance
	if an officer of the Fund	o Tax compliance, tax returns, excise
	determines that using the	tax returns and support
	Fund’s auditor to provide	o Tax opinions
	these services creates
	significant synergy in
	the form of efficiency,
	minimized disruption, or
	the ability to maintain a
	desired level of
	confidentiality.


AUDIT COMMITTEE APPROVAL POLICY	AUDIT COMMITTEE REPORTING POLICY
o “One-time” pre-approval	o A summary of
for the fund fiscal year	all such services and
within a specified dollar limit	related fees
	(including comparison
	to specified dollar
	limits) reported
	quarterly.

o Specific approval is
needed to exceed the
pre-approved dollar limits for
these services (see general
Audit Committee approval policy
below for details on obtaining
specific approvals)

o Specific approval is
needed to use the Fund’s
auditors for tax services not
denoted as pre-approved, or to
add a specific service subcategory as
“pre-approved”

SECTION III - POLICY DETAIL, CONTINUED


SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION	SPECIFIC PRE-APPROVED SERVICE
		SUBCATEGORIES
IV. OTHER SERVICES	Services which are not	o Business Risk Management support
	prohibited by the Rule,	o Other control and regulatory
A. SYNERGISTIC,	if an officer of the Fund	compliance projects
UNIQUE QUALIFICATIONS	determines that using the
	Fund’s auditor to provide
	these services creates
	significant synergy in
	the form of efficiency,
	minimized disruption,
	the ability to maintain a
	desired level of
	confidentiality, or where
	the Fund’s auditors
	posses unique or superior
	qualifications to provide
	these services, resulting
	in superior value and
	results for the Fund.


AUDIT COMMITTEE APPROVAL POLICY	AUDIT COMMITTEE REPORTING POLICY
o “One-time” pre-approval	o A summary of
for the fund fiscal year within	all such services and
a specified dollar limit	related fees
	(including comparison
	to specified dollar
	limits) reported
	quarterly.
o Specific approval is
needed to exceed the
pre-approved dollar limits for
these services (see general
Audit Committee approval policy
below for details on obtaining
specific approvals)

o Specific approval is
needed to use the Fund’s
auditors for “Synergistic” or
“Unique Qualifications” Other
Services not denoted as
pre-approved to the left, or to
add a specific service
subcategory as “pre-approved”

SECTION III - POLICY DETAIL, CONTINUED


SERVICE CATEGORY	SERVICE CATEGORY DESCRIPTION	SPECIFIC PROHIBITED SERVICE
		SUBCATEGORIES
PROHIBITED SERVICES	Services which result	1. Bookkeeping or other services
	in the auditors losing	related to the accounting records or
	independence status	financial statements of the audit
	under the Rule.	client*
		2. Financial information systems design
		and implementation*
		3. Appraisal or valuation services,
		fairness* opinions, or
		contribution-in-kind reports
		4. Actuarial services (i.e., setting
		actuarial reserves versus actuarial
		audit work)*
		5. Internal audit outsourcing services*
		6. Management functions or human
		resources
		7. Broker or dealer, investment
		advisor, or investment banking services
		8. Legal services and expert services
		unrelated to the audit
		9. Any other service that the Public
		Company Accounting Oversight Board
		determines, by regulation, is
		impermissible


AUDIT COMMITTEE APPROVAL POLICY	AUDIT COMMITTEE REPORTING POLICY
o These services are not to be	o A summary of all
performed with the exception of the(*)	services and related
services that may be permitted	fees reported at each
if they would not be subject to audit	regularly scheduled
procedures at the audit client (as	Audit Committee meeting
defined in rule 2-01(f)(4)) level	will serve as continual
the firm providing the service.	confirmation that has
	not provided any
	restricted services.

GENERAL AUDIT COMMITTEE APPROVAL POLICY:

o For all projects, the officers of the Funds and the Fund’s auditors will each make an assessment to determine that any proposed projects will not impair independence.

o Potential services will be classified into the four non-restricted service categories and the “Approval of Audit, Audit-Related, Tax and Other Services” Policy above will be applied. Any services outside the specific pre-approved service subcategories set forth above must be specifically approved by the Audit Committee.

o At least quarterly, the Audit Committee shall review a report summarizing the services by service category, including fees, provided by the Audit firm as set forth in the above policy.

(2) Disclose the percentage of services described in each of paragraphs (b) through (d) of this Item that were approved by the audit committee pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

Non-Audit Services

Beginning with non-audit service contracts entered into on or after May 6, 2003, the effective date of the

new SEC pre-approval rules, the Trust's audit committee is required to pre-approve services to

affiliates defined by SEC rules to the extent that the services are determined to have a direct impact on the operations or financial reporting of the Trust. For the years ended July 31 2021 and 2020, there were no services provided to an affiliate that required the Trust's audit committee pre-approval.

(f) If greater than 50 percent, disclose the percentage of hours expended on the principal accountants engagement to audit the registrant’s financial statements for the most recent fiscal year that were attributed to work performed by persons other than the principal accountant’s full-time, permanent employees.

N/A

(g) Disclose the aggregate non-audit fees billed by the registrants accountant for services rendered to the registrant, and rendered to the registrants investment adviser (not including any sub-adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant for each of the last two fiscal years of the registrant.

The Trust paid aggregate non-audit fees to Ernst & Young LLP for tax services of $8,189 and $8,189 during the fiscal years ended July 31, 2021 and 2020, respectively.

(h) Disclose whether the registrants audit committee of the board of trustees has considered whether the provision of non-audit services that were rendered to the registrants investment adviser (not including any subadviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant’s independence.

The Fund’s audit committee of the Board of Trustees has considered whether the provision of non-audit services that were rendered to the Affiliates (as defined) that were not pre- approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant’s independence.

ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS

(a) If the registrant is a listed issuer as defined in Rule 10A-3 under the Exchange Act (17 CFR 240.10A-3), state whether or not the registrant has a separately-designated standing audit committee established in accordance with Section 3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)). If the registrant has such a committee, however designated, identify each committee member. If the entire board of directors is acting as the registrant’s audit committee as specified in Section 3(a)(58)(B) of the Exchange Act (15 U.S.C. 78c(a)(58)(B)), so state.

N/A

(b) If applicable, provide the disclosure required by Rule 10A-3(d) under the Exchange Act (17 CFR 240.10A-3(d)) regarding an exemption from the listing standards for audit committees.

N/A

ITEM 6. SCHEDULE OF INVESTMENTS.

File Schedule of Investments in securities of unaffiliated issuers as of the close of the reporting period as set forth in 210.1212 of Regulation S-X [17 CFR 210.12-12], unless the schedule is included as part of the report to shareholders filed under Item 1 of this Form.

Included in Item 1

ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

A closed-end management investment company that is filing an annual report on this Form N-CSR must, unless it invests exclusively in non-voting securities, describe the policies and procedures that it uses to determine how to vote proxies relating to portfolio securities, including the procedures that the company uses when a vote presents a conflict between the interests of its shareholders, on the one hand, and those of the company’s investment adviser; principal underwriter; or any affiliated person (as defined in Section 2(a)(3) of the Investment Company Act of 1940 (15 U.S.C. 80a-2(a)(3)) and the rules thereunder) of the company, its investment adviser, or its principal underwriter, on the other. Include any policies and procedures of the company’s investment adviser, or any other third party, that the company uses, or that are used on the company’s behalf, to determine how to vote proxies relating to portfolio securities.

Not applicable to open-end management investment companies.

ITEM 8. PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

(a) If the registrant is a closed-end management investment company that is filing an annual report on this Form N-CSR, provide the following information:

(1) State the name, title, and length of service of the person or persons employed by or associated with the registrant or an investment adviser of the registrant who are primarily responsible for the day-to-day management of the registrant’s portfolio (“Portfolio Manager”). Also state each Portfolio Manager’s business experience during the past 5 years.

Not applicable to open-end management investment companies.

ITEM 9. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS.

(a) If the registrant is a closed-end management investment company, in the following tabular format, provide the information specified in paragraph (b) of this Item with respect to any purchase made by or on behalf of the registrant or any affiliated purchaser, as defined in Rule 10b-18(a)(3) under the Exchange Act (17 CFR 240.10b-18(a)(3)), of shares or other units of any class of the registrant’s equity securities that is registered by the registrant pursuant to Section 12 of the Exchange Act (15 U.S.C. 781).

Not applicable to open-end management investment companies.

ITEM 10. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

Describe any material changes to the procedures by which shareholders may recommend nominees to the registrant’s board of directors, where those changes were implemented after the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R(17 CFR 229.407)(as required by Item 22(b)(15)) of Schedule 14A (17 CFR 240.14a-101), or this Item.

There have been no material changes to the procedures by which the shareholders may recommend nominees to the registrant’s board of directors since the registrant last provided disclosure in response to the requirements of Item 407(c)(2)(iv) of Regulation S-R of Schedule 14(A) in its definitive proxy statement, or this item.

ITEM 11. CONTROLS AND PROCEDURES.

(a) Disclose the conclusions of the registrant’s principal executive and principal financials officers, or persons performing similar functions, regarding the effectiveness of the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Act (17 CFR 270.30a-3(c))) as of a date within 90 days of the filing date of the report that includes the disclosure required by this paragraph, based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the Act (17 CFR 270.30(a)-3(b) and Rules 13a-15(b) or 15d-15(b) under the Exchange Act (17 CFR 240.13a-15(b) or 240.15d-15(b)).

The registrant’s principal executive officer and principal financial officer have concluded that the registrant’s disclosure controls and procedures are effective based on the evaluation of these controls and procedures as of a date within 90 days of the filing date of this report.

(b) Disclose any change in the registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the Act (17CFR 270.30a-3(d)) that occured during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

There were no significant changes in the registrant’s internal control over financial reporting that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Disclosure of Securities Lending Activities for Closed-End Management Investment Companies.

(a) If the registrant is a closed-end management investment company, provide the following dollar amounts of income and compensation related to the securities lending activities of the registrant during its most recent fiscal year:

N/A

(1) Gross income from securities lending activities;

N/A

(2) All fees and/or compensation for each of the following securities lending activities and related services: any share of revenue generated by the securities lending program paid to the securities lending agent(s) (revenue split); fees paid for cash collateral management services (including fees deducted from a pooled cash collateral reinvestment vehicle) that are not included in the revenue split; administrative fees that are not included in the revenue split; fees for indemnification that are not included in the revenue split; rebates paid to borrowers; and any other fees relating to the securities lending program that are not included in the revenue split, including a description of those other fees;

N/A

(3) The aggregate fees/compensation disclosed pursuant to paragraph (2); and

N/A

(4) Net income from securities lending activities (i.e., the dollar amount in paragraph (1) minus the dollar amount in paragraph (3)).

If a fee for a service is included in the revenue split, state that the fee is included in the revenue split.

N/A

(b) If the registrant is a closed-end management investment company, describe the services provided to the registrant by the securities lending agent in the registrants most recent fiscal year.

N/A

ITEM 13. EXHIBITS.

(a) File the exhibits listed below as part of this Form. Letter or number the exhibits in the sequence indicated.

(1) Any code of ethics, or amendment thereto, that is the subject of the disclosure required by Item 2, to the extent that the registrant intends to satisfy the Item 2 requirements through filing of an exhibit.

(2) A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2(a)) , exactly as set forth below:

Filed herewith.

SIGNATURES

[See General Instruction F]

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant) Pioneer Asset Allocation Trust

By (Signature and Title)* /s/ Lisa M. Jones

Lisa M. Jones, President and Chief Executive Officer

Date October 5, 2021

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)* /s/ Lisa M. Jones

Lisa M. Jones, President and Chief Executive Officer

Date October 5, 2021

By (Signature and Title)* /s/ Anthony J. Koenig, Jr.

Anthony J. Koenig, Jr., Treasurer and Chief Financial and Accounting Officer

Date October 5, 2021

* Print the name and title of each signing officer under his or her signature.

Pioneer Asset Allocation Trust N-CSRCertified annual shareholder report (management investment company)