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: 811-02383

AB BOND FUND, INC.

(Exact name of registrant as specified in charter)

1345 Avenue of the Americas, New York, New York 10105

(Address of principal executive offices) (Zip code)

Joseph J. Mantineo

AllianceBernstein L.P.

1345 Avenue of the Americas

New York, New York 10105

(Name and address of agent for service)

Registrant’s telephone number, including area code: (800) 221-5672

Date of fiscal year end: October 31, 2022

Date of reporting period: April 30, 2022

ITEM 1. REPORTS TO STOCKHOLDERS.

APR    ^04.30.22

SEMI-ANNUAL REPORT

AB ALL MARKET REAL RETURN PORTFOLIO

As of January 1, 2021, as permitted by new regulations adopted by the Securities and Exchange Commission, the Fund’s annual and semi-annual shareholder reports are no longer sent by mail, unless you specifically requested paper copies of the reports. Instead, the reports are made available on a website, and you will be notified by mail each time a report is posted and provided with a website address to access the report.

You may elect to receive all future reports in paper form free of charge. 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; if you invest directly with the Fund, you can call the Fund at (800) 221 5672. Your election to receive reports in paper form will apply to all funds held in your account with your financial intermediary or, if you invest directly, to all AB Mutual Funds you hold.

Investors should consider the investment objectives, risks, charges and expenses of the Fund carefully before investing. For copies of our prospectus or summary prospectus, which contain this and other information, visit us online at www.abfunds.com or contact your AB representative. Please read the prospectus and/or summary prospectus carefully before investing.

This shareholder report must be preceded or accompanied by the Fund’s prospectus for individuals who are not current shareholders of the Fund.

You may obtain a description of the Fund’s proxy voting policies and procedures, and information regarding how the Fund voted proxies relating to portfolio securities during the most recent 12-month period ended June 30, without charge. Simply visit AB’s website at www.abfunds.com, or go to the Securities and Exchange Commission’s (the “Commission”) website at www.sec.gov, or call AB at (800) 227 4618.

The Fund files its complete schedule of portfolio holdings with the Commission for the first and third quarters of each fiscal year as an exhibit to its reports on Form N-PORT. The Fund’s Form N-PORT reports are available on the Commission’s website at www.sec.gov. AB publishes full portfolio holdings for the Fund monthly at www.abfunds.com.

AllianceBernstein Investments, Inc. (ABI) is the distributor of the AB family of mutual funds. ABI is a member of FINRA and is an affiliate of AllianceBernstein L.P., the Adviser of the funds.

The [A/B] logo is a registered service mark of AllianceBernstein and AllianceBernstein^® is a registered service mark used by permission of the owner, AllianceBernstein L.P.

FROM THE PRESIDENT

Dear Shareholder,

We’re pleased to provide this report for the AB All Market Real Return Portfolio (the “Fund”). Please review the discussion of Fund performance, the market conditions during the reporting period and the Fund’s investment strategy.

At AB, we’re striving to help our clients achieve better outcomes by:

Whether you’re an individual investor or a multibillion-dollar institution, we’re putting our knowledge and experience to work for you every day.

For more information about AB’s comprehensive range of products and shareholder resources, please log on to www.abfunds.com.

Thank you for your investment in AB mutual funds—and for placing your trust in our firm.

Sincerely,

Onur Erzan

President and Chief Executive Officer, AB Mutual Funds

SEMI-ANNUAL REPORT

June 8, 2022

This report provides management’s discussion of fund performance for the AB All Market Real Return Portfolio for the semi-annual reporting period ended April 30, 2022.

The Fund’s investment objective is to maximize real return over inflation.

NAV RETURNS AS OF APRIL 30, 2022 (unaudited)

Please keep in mind that high, double-digit returns are highly unusual and cannot be sustained. Investors should also be aware that these returns were primarily achieved during favorable market conditions.

INVESTMENT RESULTS

The table above shows the Fund’s performance compared to its benchmark, the Morgan Stanley Capital International All Country (“MSCI AC”) World Commodity Producers Index (net), for the six- and 12-month periods ended April 30, 2022.

All share classes of the Fund underperformed the benchmark for both periods, before sales charges. During the six-month period, the strategic allocation detracted overall, relative to the benchmark, as real estate investment trusts (“REITs”) and inflation-sensitive equities underperformed commodity producers. This was partially offset by the strategic allocation

to commodity futures, which contributed by significantly outperforming commodity producers. Security selection within commodity producers and commodity futures detracted, while security selection within REITs contributed. The Fund’s tactical overweights to commodity equities and commodity futures contributed, as did tactical underweights to inflation-sensitive equities and REITs.

For the 12-month period, the strategic allocation detracted overall, as REITs and inflation-sensitive equities underperformed commodity producers. This was partially offset by the strategic allocation to commodity futures, which contributed by significantly outperforming commodity producers. Security selection within REITs and inflation-sensitive equities contributed, while security selection within commodity equities detracted. The Fund’s tactical overweights to commodity futures and commodity equities contributed, as did tactical underweights to inflation-sensitive equities and REITs.

The Fund utilized derivatives for hedging and investment purposes in the form of futures, currency forwards, inflation swaps and variance swaps, which added to absolute returns for both periods, while total return swaps added for the six-month period, and detracted for the 12-month period.

MARKET REVIEW AND INVESTMENT STRATEGY

US, international and emerging-market stocks lost ground during the six-month period ended April 30, 2022. Early in the period, equities continued to benefit from accommodative monetary policy that underpinned an accelerating global economic recovery. Volatility increased as rapidly rising inflation triggered a hawkish shift among most major central banks. Inflation worsened after Russia’s invasion of Ukraine caused energy and agricultural prices to surge and China’s pledge to enforce its zero-COVID policy raised new supply-chain concerns. The US Federal Reserve raised interest rates in March and signaled that it would move aggressively to harness inflation. The growing risk of recession led to sharp declines across global equity markets. Against a backdrop of rising rates, growth stocks came under pressure, triggering a rotation into value-oriented stocks. Within large-cap markets, value stocks outperformed growth stocks by a wide margin, although both declined in absolute terms. Large-cap stocks outperformed small-cap stocks on a relative basis, but both declined in absolute terms.

Fixed-income government bond market yields spiked in most markets, which led bond prices to fall on inflation concerns in all regions. Relative government bond returns were led by global inflation-linked bonds. Global investment-grade corporate bonds, which typically have longer maturities and are more sensitive to changes in yields than high-yield corporates, trailed global treasuries by a wide margin, except in the eurozone. High-yield corporate bonds also underperformed treasuries, but by a smaller margin. However, high-yield euro-denominated corporates outperformed eurozone treasuries during the period due to ongoing support from the

European Central Bank. Emerging-market bonds underperformed the most as the US dollar advanced against most developed- and emerging-market currencies. Securitized assets also underperformed treasuries, but by a lesser extent than investment-grade corporates, given their lower sensitivity to yield changes. Brent crude oil prices rose sharply because of supply concerns and increased demand.

Inflation assets were mixed over the six- and 12-month periods, with natural resource equities, commodities and inflation swaps rallying. REITs posted negative returns over the six-month period and were close to neutral over the 12-month period, with the asset class outperforming broader equity markets over both periods. Commodities and natural resource equities rose meaningfully over both periods as strong demand from the global reopening combined with the conflict between Russia and Ukraine—both major exporters of key commodities—exacerbated supply concerns in already-tight markets, such as oil, gas and agricultural commodities, further elevating prices. Inflation swaps continued to climb as inflation concerns remained at the forefront for investors.

The Fund’s Senior Investment Management Team continues to look for sources of value via asset allocation shifts, active security selection, risk overlay strategies and currency management. The Fund uses a blend of quantitative and fundamental research in order to determine overall portfolio risk, allocate risk across major real asset classes and identify idiosyncratic opportunities.

INVESTMENT POLICIES

The Fund seeks to maximize real return. Real return is the rate of return after adjusting for inflation. The Fund pursues an aggressive investment strategy involving a variety of asset classes. The Fund invests primarily in instruments that the Adviser expects to outperform broad equity indices during periods of rising inflation. Under normal circumstances, the Fund expects to invest its assets principally in the following instruments that, in the judgment of the Adviser, are affected directly or indirectly by the level and change in rate of inflation: inflation-indexed fixed-income securities, such as Treasury inflation-protected securities (“TIPS”) and similar bonds issued by governments outside of the United States; commodities; commodity-related equity securities; real estate equity securities; inflation-sensitive equity securities, which the Fund defines as equity securities of companies that the Adviser believes have the ability to pass along increasing costs to consumers and maintain or grow margins in rising inflation environments, including equity securities of utilities and infrastructure-related companies (“inflation-sensitive equities”); securities and derivatives linked to the price of other assets (such as commodities, stock indices

(continued on next page)

and real estate); and currencies. The Fund expects its investments in fixed-income securities to have a broad range of maturities and quality levels.

The Fund seeks inflation protection from investments around the globe, both in developed- and emerging-market countries. In selecting securities for purchase and sale, the Adviser utilizes its qualitative and quantitative resources to determine overall inflation sensitivity, asset allocation and security selection. The Adviser assesses the securities’ risks and inflation sensitivity as well as the securities’ impact on the overall risks and inflation sensitivity of the Fund. When its analysis indicates that changes are necessary, the Adviser intends to implement them through a combination of changes to underlying positions and the use of inflation swaps and other types of derivatives, such as interest rate swaps.

The Fund anticipates that its targeted investment mix, other than its investments in inflation-indexed fixed-income securities, will focus on commodity-related equity securities, commodities and commodity derivatives, real estate equity securities and inflation-sensitive equities to provide a balance between expected return and inflation protection. The Fund may vary its investment allocations among these asset classes, at times significantly. Its commodities investments will include significant exposure to energy commodities, but will also include agricultural products, and industrial and precious metals, such as gold. The Fund’s investments in real estate equity securities will include REITs and other real estate-related securities.

The Fund invests in both US and non-US dollar-denominated equity or fixed-income securities. The Fund may invest in currencies for hedging or investment purposes, both in the spot market and through long or short positions in currency-related derivatives. The Fund does not ordinarily expect to hedge its foreign currency exposure because it will be balanced by investments in US dollar-denominated securities, although it may hedge the exposure under certain circumstances.

The Fund may enter into derivatives, such as options, futures contracts, forwards, swaps or structured notes, to a significant extent, subject to the limits of applicable law. The Fund intends to use leverage for investment purposes through the use of cash made available by derivatives transactions to make other investments in accordance with its investment policies. In determining when and to what extent to employ leverage or enter into derivatives transactions, the Adviser considers factors such as the relative risks and returns expected of potential investments and the cost of such transactions. The Adviser

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considers the impact of derivatives in making its assessments of the Fund’s risks. The resulting exposures to markets, sectors, issuers or specific securities will be continuously monitored by the Adviser.

The Fund may seek to gain exposure to physical commodities traded in the commodities markets through use of a variety of derivative instruments, including investments in commodity index-linked notes. The Adviser expects that the Fund will seek to gain exposure to commodities and commodity-related instruments and derivatives primarily through investments in AllianceBernstein Cayman Inflation Strategy, Ltd., a wholly owned subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”). The Subsidiary is advised by the Adviser and has the same investment objective and substantially similar investment policies and restrictions as the Fund except that the Subsidiary, unlike the Fund, may invest, without limitation, in commodities and commodity-related instruments. The Fund is subject to the risks associated with the commodities, derivatives and other instruments in which the Subsidiary invests, to the extent of its investment in the Subsidiary. The Fund limits its investment in the Subsidiary to no more than 25% of its net assets. Investment in the Subsidiary is expected to provide the Fund with commodity exposure within the limitations of federal tax requirements that apply to the Fund.

The Fund is “non-diversified”, which means that it may concentrate its assets in a smaller number of issuers than a diversified fund.

DISCLOSURES AND RISKS

Benchmark Disclosure

The MSCI AC World Commodity Producers Index is unmanaged and does not reflect fees and expenses associated with the active management of a mutual fund portfolio. The MSCI AC World Commodity Producers Index is a free float-adjusted, market capitalization index designed to track the performance of global listed commodity producers, including emerging markets. Commodities sectors include: energy, grains, industrial metals, petroleum, precious metals and softs. MSCI makes no express or implied warranties or representations, and shall have no liability whatsoever with respect to any MSCI data contained herein. The MSCI data may not be further redistributed or used as a basis for other indices, any securities or financial products. This report is not approved, reviewed or produced by MSCI. Net returns include the reinvestment of dividends after deduction of non-US withholding tax. An investor cannot invest directly in an index, and its results are not indicative of the performance for any specific investment, including the Fund.

A Word About Risk

Market Risk: The value of the Fund’s assets will fluctuate as the stock, commodity and bond markets fluctuate. The value of the Fund’s investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events, including public health crises (including the occurrence of a contagious disease or illness) and regional and global conflicts, that affect large portions of the market.

Credit Risk: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security and accrued interest. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations.

Interest-Rate Risk: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of existing investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest-rate risk is generally greater for fixed-income securities with longer maturities or durations. The current historically low interest rate environment heightens the risks associated with rising interest rates.

DISCLOSURES AND RISKS (continued)

Commodity Risk: Investing in commodities and commodity-linked derivative instruments, either directly or through the Subsidiary, may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative instruments may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Derivatives Risk: Derivatives may be difficult to price or unwind and leveraged so that small changes may produce disproportionate losses for the Fund. Derivatives, especially over-the-counter derivatives, are also subject to counterparty risk, which is the risk that the counterparty (the party on the other side of the transaction) on a derivative transaction will be unable or unwilling to honor its contractual obligations to the Fund.

Leverage Risk: To the extent the Fund uses leveraging techniques, its net asset value (“NAV”) may be more volatile because leverage tends to exaggerate the effect of changes in interest rates and any increase or decrease in the value of the Fund’s investments.

Inflation Risk: This is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the value of the Fund’s assets can decline as can the value of the Fund’s distributions. This risk is significantly greater for fixed-income securities with longer maturities.

Illiquid Investments Risk: Illiquid investments risk exists when certain investments are or become difficult to purchase or sell. Difficulty in selling such investments may result in sales at disadvantageous prices affecting the value of your investment in the Fund. Causes of illiquid investments risk may include low trading volumes and large positions. Foreign fixed-income securities may have more illiquid investments risk because secondary trading markets for these securities may be smaller and less well-developed and the securities may trade less frequently. Illiquid investments risk may be higher in a rising interest-rate environment, when the value and liquidity of fixed-income securities generally go down.

Foreign (Non-US) Risk: Investments in securities of non-US issuers may involve more risk than those of US issuers. These securities may fluctuate more widely in price and may be more difficult to trade due to adverse market, economic, political, regulatory or other factors.

Currency Risk: Fluctuations in currency exchange rates may negatively affect the value of the Fund’s investments or reduce its returns.

DISCLOSURES AND RISKS (continued)

Subsidiary Risk: By investing in the Subsidiary, the Fund is indirectly exposed to the risks associated with the Subsidiary’s investments. The derivatives and other investments held by the Subsidiary are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund. The Subsidiary is not registered under the Investment Company Act of 1940, as amended (the “1940 Act”), and, unless otherwise noted in the Fund’s prospectus, is not subject to all of the investor protections of the 1940 Act. However, the Fund wholly owns and controls the Subsidiary, and the Fund and the Subsidiary are managed by the Adviser, making it unlikely the Subsidiary will take actions contrary to the interests of the Fund or its shareholders.

Real Estate Risk: The Fund’s investments in real estate securities have many of the same risks as direct ownership of real estate, including the risk that the value of real estate could decline due to a variety of factors that affect the real estate market generally. Investments in REITs may have additional risks. REITs are dependent on the capability of their managers, may have limited diversification, and could be significantly affected by changes in taxes.

Non-Diversification Risk: The Fund may have more risk because it is “non-diversified”, meaning that it can invest more of its assets in a smaller number of issuers. Accordingly, changes in the value of a single security may have a more significant effect, either negative or positive, on the Fund’s NAV.

Management Risk: The Fund is subject to management risk because it is an actively managed investment fund. The Adviser will apply its investment techniques and risk analyses in making investment decisions, but there is no guarantee that its techniques will produce the intended results. Some of these techniques may incorporate, or rely upon, quantitative models, but there is no guarantee that these models will generate accurate forecasts, reduce risk or otherwise perform as expected.

These risks are fully discussed in the Fund’s prospectus. As with all investments, you may lose money by investing in the Fund.

An Important Note About Historical Performance

The investment return and principal value of an investment in the Fund will fluctuate, so that shares, when redeemed, may be worth more or less than their original cost. Performance shown in this report represents past performance and does not guarantee future results. Current performance may be lower or higher than the performance information shown. You may obtain performance information current to the most recent month-end by visiting

DISCLOSURES AND RISKS (continued)

www.abfunds.com. For Class 1 shares, go to www.bernstein.com and click on “Investments”, found in the footer, then “Mutual Fund Information—Mutual Fund Performance at a Glance.”

Investors should consider the investment objectives, risks, charges and expenses of the Fund carefully before investing. For copies of our prospectus or summary prospectus, which contain this and other information, visit us online at www.abfunds.com. For Class 1 shares, go to www.bernstein.com, click on “Investments”, found in the footer, then “Mutual Fund Information—Prospectuses, SAIs and Shareholder Reports.” Please read the prospectus and/or summary prospectus carefully before investing.

All fees and expenses related to the operation of the Fund have been deducted. NAV returns do not reflect sales charges; if sales charges were reflected, the Fund’s quoted performance would be lower. SEC returns reflect the applicable sales charges for each share class: a 4.25% maximum front-end sales charge for Class A shares and a 1% 1-year contingent deferred sales charge for Class C shares. Returns for the different share classes will vary due to different expenses associated with each class. Performance assumes reinvestment of distributions and does not account for taxes.

HISTORICAL PERFORMANCE

AVERAGE ANNUAL RETURNS AS OF APRIL 30, 2022 (unaudited)

(footnotes continued on next page)

HISTORICAL PERFORMANCE (continued)

The Fund’s prospectus fee table shows the Fund’s total annual operating expense ratios as 1.13%, 0.87%, 1.18%, 1.93%, 0.92%, 1.60%, 1.31%, 0.88% and 0.88% for Class 1, Class 2, Class A, Class C, Advisor Class, Class R, Class K, Class I and Class Z shares, respectively, gross of any fee waivers or expense reimbursements. Contractual fee waivers and/or expense reimbursements limit the Fund’s annual operating expense ratio (excluding extraordinary expenses, interest expense, and acquired fund fees and expenses other than the advisory fees of any AB mutual funds in which the Fund may invest) to 1.55% for Class R shares. These waivers/reimbursements may not be terminated before January 31, 2023, and may be extended by the Adviser for additional one-year terms. Absent reimbursements or waivers, performance would have been lower. The Financial Highlights section of this report sets forth expense ratio data for the current reporting period; the expense ratios shown above may differ from the expense ratios in the Financial Highlights section since they are based on different time periods.

HISTORICAL PERFORMANCE (continued)

SEC AVERAGE ANNUAL RETURNS

AS OF THE MOST RECENT CALENDAR QUARTER-END

MARCH 31, 2022 (unaudited)

(footnotes continued on next page)

HISTORICAL PERFORMANCE (continued)

EXPENSE EXAMPLE

(unaudited)

As a shareholder of a mutual fund, you may incur two types of costs: (1) transaction costs, including sales charges (loads) on purchase payments, contingent deferred sales charges on redemptions and (2) ongoing costs, including management fees; distribution (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (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 invested at the beginning of the period and held for the entire period as indicated below.

Actual Expenses

The table below provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

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 annual rate of return of 5% 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 by comparing this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads), or contingent deferred sales charges on redemptions. Therefore, the hypothetical example 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 transactional costs were included, your costs would have been higher.

EXPENSE EXAMPLE (continued)

PORTFOLIO SUMMARY

April 30, 2022 (unaudited)

PORTFOLIO STATISTICS

Net Assets ($mil): $1,262.4

PORTFOLIO SUMMARY (continued)

April 30, 2022 (unaudited)

TEN LARGEST HOLDINGS²

CONSOLIDATED PORTFOLIO OF INVESTMENTS

April 30, 2022 (unaudited)

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