BioAtla (BCAB) 424B5 Prospectus supplement for primary offering

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-262528

PROSPECTUS SUPPLEMENT

(To Prospectus dated May 18, 2022)

$100,000,000

Common Stock

We have entered into an Open Market Sale Agreement^SM, or the sales agreement, with Jefferies LLC, or Jefferies, dated January 6, 2023, relating to the sale of shares of our common stock offered by this prospectus supplement. In accordance with the terms of the sales agreement, under this prospectus supplement, we may offer and sell shares of our common stock, $0.0001 par value per share, having an aggregate offering price of up to $100,000,000 from time to time through Jefferies, acting as our sales agent.

Our common stock is listed on The Nasdaq Global Market under the symbol “BCAB.” On January 5, 2023, the last reported sale price of our common stock on The Nasdaq Global Market was $8.25 per share.

Sales of shares of our common stock, if any, under this prospectus will be made by any method permitted that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended, or the Securities Act. Jefferies is not required to sell any specific number or dollar amount of securities, but will act as a sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between Jefferies and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

Jefferies will be entitled to compensation under the terms of the sales agreement at a fixed commission rate equal to 3% of the gross proceeds of any shares of common stock sold under the sales agreement. In connection with the sale of shares of our common stock on our behalf, Jefferies may be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Jefferies may be deemed to be underwriting commissions or discounts. See “Plan of Distribution” beginning on page S-12 for additional information regarding the compensation to be paid to Jefferies. We have also agreed to provide indemnification and contribution to Jefferies against certain liabilities, including liabilities under the Securities Act and the Securities Exchange Act of 1934, as amended, or the Exchange Act.

We are a “smaller reporting company” under the federal securities laws and, as such, we have elected to comply with certain reduced public company reporting requirements for this prospectus and for future filings. See “Prospectus Summary—Implications of Being a Smaller Reporting Company.”

Investing in our common stock involves a high degree of risk. You should carefully consider the risks described under the heading “Risk Factors” beginning on page S-5 of this prospectus supplement and the documents incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense. Any representation to the contrary is a criminal offense.

Jefferies

The date of this prospectus supplement is January 6, 2023

TABLE OF CONTENTS

	Page
About This Prospectus Supplement		S-ii
Forward-Looking Statements		S-iv
Prospectus Supplement Summary		S-1
The Offering		S-3
Risk Factors		S-5
Use of Proceeds		S-10
Dividend Policy		S-11
Plan of Distribution		S-12
Legal Matters		S-14
Experts		S-15
Incorporation of Certain Information by Reference		S-16
Where You Can Find More Information		S-17

TABLE OF CONTENTS

	Page
About This Prospectus		1
BioAtla, Inc.		2
Risk Factors		3
Cautionary Statement Regarding Forward-Looking Statements		4
Use of Proceeds		5
Description of Our Capital Stock		6
Description of Our Debt Securities		11
Description of Our Warrants		12
Description of Our Units		13
Plan of Distribution		14
Legal Matters		15
Experts		15
Where You Can Find Additional Information		15
Incorporation of Certain Information by Reference		16

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ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 (File No. 333-262528) that we filed with the Securities and Exchange Commission (the “SEC”) using a “shelf” registration process. Under this shelf registration process, we may sell shares of our common stock, preferred stock, debt securities, warrants, and units under the prospectus included in the registration statement from time to time at prices and on terms to be determined by market conditions at the time of the offering described in the accompanying prospectus.

This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering of common stock and also adds to and updates the information contained in the accompanying prospectus and the documents incorporated by reference herein and therein. The second part, the accompanying prospectus, provides more general information, some of which may not apply to this offering. Generally, when we refer to this prospectus, we are referring to this prospectus supplement and the accompanying prospectus combined. To the extent there is a conflict between the information contained in this prospectus supplement and the information contained in the accompanying prospectus or any document incorporated by reference herein or therein filed prior to the date of this prospectus supplement, you should rely on the information in this prospectus supplement; provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

Neither we nor Jefferies has authorized any other party to provide you with information that is different from or in addition to the information contained in, or incorporated by reference into, this prospectus supplement, the accompanying prospectus, or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. Neither we nor Jefferies is making an offer to sell shares of our common stock in any jurisdiction where the offer or sale is not permitted.

Before purchasing any securities, you should carefully read both this prospectus supplement, the accompanying prospectus and any free writing prospectus, together with the additional information described under the heading “Incorporation of Certain Information by Reference.” You should assume that the information contained in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference herein and therein or any free writing prospectus is accurate only as of the date on its respective cover, and that any information incorporated by reference is accurate only as of the date of the document incorporated by reference, unless we indicate otherwise. Our business, financial condition, results of operations and prospects may have changed since those dates.

This prospectus supplement and the accompanying prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus supplement is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information.” This prospectus supplement, the accompanying prospectus or any free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate. We are not making offers to sell any securities described in this prospectus supplement in any jurisdiction in which an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation.

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Unless the context otherwise indicates, references in this prospectus supplement and the accompanying prospectus to “BioAtla”, the “Company”, “we”, “us” and “our” refer to BioAtla, Inc., a Delaware corporation, together with its consolidated subsidiaries. BioAtla is a trademark of BioAtla, Inc. Our logos and trademarks are the property of BioAtla. All other brand names or trademarks appearing in this prospectus supplement and the accompanying prospectus are the property of their respective holders. Use or display by us of other parties’ trademarks or trade dress in this prospectus supplement and the accompanying prospectus is not intended to, and does not, imply a relationship with, or endorsements or sponsorship of us by the trademark or trade dress owners.

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FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the other documents that are incorporated herein or therein by reference contain forward-looking statements. We may, in some cases, use words such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “will,” “would” or the negative of those terms, and similar expressions that convey uncertainty of future events or outcomes to identify these forward-looking statements. Any statements contained herein that are not statements of historical facts may be deemed to be forward-looking statements.

We have based these forward-looking statements largely on our current expectations and projections about future events and trends that we believe may affect our financial condition, results of operations, business strategy short-term and long-term business operations and objectives and financial needs. These forward-looking statements are subject to known and unknown risks, uncertainties and assumptions, including risks described in the “Risk Factors” section of this prospectus supplement and the documents incorporated by reference into this prospectus supplement. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the future events and trends discussed in this prospectus supplement, the accompanying prospectus and the other documents that are incorporated herein or therein by reference may not occur, and actual results may differ materially and adversely from those anticipated or implied in the forward-looking statements. Such forward-looking statements include, but are not limited to, statements about:

• our ability to develop and advance our current product candidates and programs into, and successfully complete, clinical trials;

• the ability of our clinical trials to demonstrate safety and efficacy of our product candidates and other positive results;

• the size of the market opportunity for our product candidates, including our estimates of the number of patients who suffer from the diseases we are targeting;

• our manufacturing, commercialization and marketing capabilities and strategy;

• our plans and strategies to develop and commercialize our CAB antibodies;

• our plans to further develop our technology platform and expand our pipeline of product candidates;

• the potential benefits and advantages of our current and future product candidates that we may develop from our patented technology platform;

• the impact of the COVID-19 pandemic on our business, financial condition, results of operations, and prospects;

• the timing or likelihood of regulatory filings and approvals for our product candidates;

• regulatory developments in the United States and Europe and other foreign countries;

• our expectations and plans to obtain funding for our operations, including from our existing and potential future collaboration and licensing agreements;

• our expectations regarding our ability to obtain and maintain intellectual property protection for our technology platform and product candidates;

• the potential benefits of our strategic relationships and our plans to pursue additional strategic relationships;

• our continued reliance on third parties to conduct additional clinical trials of our product candidates and for the manufacture of our product candidates for preclinical studies and clinical trials; and

• our estimates regarding expenses, future revenue, capital requirements and needs for additional financing.

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We caution readers not to place undue reliance on any such forward-looking statements, which speak only as of the date they were made. We disclaim any obligation, except as specifically required by law, and the rules of the SEC, to publicly update or revise any such statements to reflect any change in our expectations or in events, conditions or circumstances on which any such statements may be based, or that may affect the likelihood that actual results will differ from those set forth in such forward-looking statements.

You should read this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein with the understanding that our actual future results may be materially different from those expressed in forward-looking statements.

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PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information contained elsewhere, or incorporated by reference, in this prospectus supplement. This summary does not contain all of the information that you should consider before deciding to invest in our common stock. For a more complete understanding of our company and this offering, you should read and consider carefully the more detailed information included or incorporated by reference in this prospectus supplement and the accompanying prospectus, including the factors described under the heading “Risk Factors” on page S-5 of this prospectus supplement and in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021 (the “Annual Report”), filed with the SEC on February 28, 2022, and in our Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2022, June 30, 2022 and September 30, 2022, respectively, each of which is incorporated by reference into this prospectus supplement and the accompanying prospectus.

Company Overview

We are a clinical-stage biopharmaceutical company developing our novel class of highly specific and selective antibody-based therapeutics for the treatment of solid tumor cancer. Our conditionally active biologics (“CAB” or “CABs”) capitalize on our proprietary discoveries with respect to tumor biology, enabling us to target known and widely validated tumor antigens that have previously been difficult or impossible to target. Our novel CAB therapeutic candidates exploit characteristic pH differences between the tumor microenvironment and healthy tissue. Unlike healthy tissue, the tumor microenvironment is acidic, and we have designed our antibodies to selectively bind to their targets on tumor cells under acidic pH conditions but not on targets in normal tissues. Our approach is to identify the necessary targeting and potency required for cancer cell destruction, while aiming to eliminate or greatly reduce on-target, off-tumor toxicity—one of the fundamental challenges of existing cancer therapies.

We are a United States-based company with research facilities in San Diego, California and, through our contractual relationship with BioDuro-Sundia, a provider of preclinical development services, in Beijing, China. Since the commencement of our operations, we have focused substantially all of our resources on conducting research and development activities, including drug discovery, preclinical studies and clinical trials of our product candidates, including the ongoing Phase 2 clinical trials of mecbotamab vedotin (BA3011) targeting AXL in sarcoma and non-small cell lung cancer (NSCLC), our investigator-initiated trials of BA3011 and BA3021 for ovarian cancer, and ozuriftamab vedotin (BA3021) targeting ROR2 in NSCLC, melanoma, and head and neck cancer (SCCHN) and our Phase 1 clinical trial of BA3071, establishing and maintaining our intellectual property portfolio, manufacturing clinical and research material through third parties, hiring personnel, establishing product development and commercialization collaborations with third parties, raising capital and providing general and administrative support for these operations. Since 2014, such research and development activities have exclusively related to the research, development, manufacture and Phase 1 and Phase 2 clinical testing of our CAB antibody-based product candidates and the strengthening of our proprietary CAB technology platform and pipeline.

Corporate Information

Our business was founded in March 2007 and originally operated as a Delaware limited liability company, BioAtla, LLC. In July 2020, we converted from a limited liability company into a Delaware corporation pursuant to a statutory conversion and changed our name from BioAtla, LLC to BioAtla, Inc. Our principal executive offices are located at 11085 Torreyana Road, San Diego, California 92121, and our telephone number is (858) 558-0708. Our corporate website address is www.bioatla.com. Information contained on, or that may be accessed through, our website is not incorporated by reference into this prospectus supplement or the underlying prospectus and should not be considered a part of either document.

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Implications of Being a Smaller Reporting Company

We are a “smaller reporting company” as defined in Rule 12b-2 promulgated under the Exchange Act. We may remain a smaller reporting company until we have a non-affiliate public float in excess of $250 million and annual revenues in excess of $100 million, or a non-affiliate public float in excess of $700 million, each as determined on an annual basis. A smaller reporting company may take advantage of relief from some of the reporting requirements and other burdens that are otherwise applicable generally to public companies. These provisions include: being permitted to provide only two years of audited financial statements, in addition to any required unaudited interim financial statements, with correspondingly reduced “Management’s Discussion and Analysis of Financial Condition and Results of Operations” disclosure; not being required to comply with the auditor attestation requirements in the assessment of our internal control over financial reporting; and reduced disclosure obligations regarding executive compensation in our periodic reports, proxy statements and registration statements.

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THE OFFERING

Common stock offered by us Shares of our common stock having an aggregate offering price of up to $100,000,000.

Common stock to be outstanding immediately after
this offering Up to 48,486,529 shares (as more fully described in the notes following this table), assuming sales of 12,121,212 shares of our common stock in this offering at an offering price of $8.25 per share, which was the last reported sale price of our common stock on The Nasdaq Global Market on January 5, 2023. The actual number of shares issued will vary depending on the sales price under this offering.

Class B common stock to be outstanding after this offering 1,211,959 shares.

Total common stock and Class B common stock to
be outstanding after this offering Up to 49,698,488 shares (as more fully described in the notes following this table), assuming sales of 12,121,212 shares of our common stock in this offering at an offering price of $8.25 per share, which was the last reported sale price of our common stock on The Nasdaq Global Market on January 5, 2023. The actual number of shares issued will vary depending on the sales price under this offering.

Plan of distribution “At the market” offering that may be made from time to time on The Nasdaq Global Market or other existing trading market for our common stock through or to Jefferies LLC, as sales agent or principal. See “Plan of Distribution” on page S-12 of this prospectus supplement.

Use of proceeds We intend to use the net proceeds we receive from any sales of our common stock in this offering, if any, together with existing cash and cash equivalents, primarily to fund our research and development efforts, including Phase 2 clinical trials and potential commercialization of mecbotamab vedotin (BA3011), Phase 2 clinical trials of ozuriftamab vedotin (BA3021), clinical development of BA3071 and BA3182, preclinical development of several of our other CAB candidates, and for working capital and other general corporate purposes. See “Use of Proceeds” on page S-10 of this prospectus supplement for additional information.

Nasdaq Global Market symbol “BCAB”

The number of shares of our common stock and Class B common stock to be outstanding immediately after this offering is based on 36,365,317 shares of our common stock outstanding as of September 30, 2022 and 1,211,959 shares of our Class B common stock outstanding as of September 30, 2022. The number of shares outstanding as of September 30, 2022, excludes:

• 2,718,930 shares of common stock issuable upon the exercise of stock options outstanding as of September 30, 2022, at a weighted average exercise price of $14.00 per share;

• 51,000 shares of common stock issuable upon the exercise of outstanding stock options granted subsequent to September 30, 2022, at a weighted average exercise price of $8.46 per share;

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• 629,007 shares of common stock issuable upon the vesting of restricted stock units outstanding as of September 30, 2022;

• 3,022,529 shares of common stock reserved for future issuance under our 2020 Equity Incentive Plan, or the 2020 Plan, as of September 30, 2022, as well as any automatic increases in the number of shares of common stock reserved for issuance under the 2020 Plan; and

• 1,208,484 shares of common stock reserved for future issuance under our 2020 Employee Stock Purchase Plan, or the 2020 ESPP, as of September 30, 2022, as well as any automatic increases in the number of shares of common stock reserved for issuance under the 2020 ESPP.

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RISK FACTORS

An investment in our common stock involves significant risks. Before making an investment in our common stock, you should carefully read all of the information contained in this prospectus supplement, the accompanying prospectus and in the documents incorporated by reference herein and therein. For a discussion of risks that you should carefully consider before deciding to purchase any of our common stock, please review the risk factors disclosed below and those incorporated by reference herein contained in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021 and in our Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2022, June 30, 2022 and September 30, 2022, respectively, together with the other information in this prospectus supplement, the accompanying prospectus, and the information and documents incorporated by reference herein and therein. Any of these risks, as well as additional risks not currently known to us or that we currently deem immaterial, may adversely affect our business, financial condition, results of operations, and prospects, resulting in a decline in the trading price of our common stock and loss of all or part of your investment.

Risks Relating to this Offering and our Common Stock

Our management will have broad discretion over the actual amount and timing of the expenditures of the proceeds we receive in this offering, if any, and might not apply these proceeds in ways that enhance our financial condition or operating results or increase the value of your investment.

We intend to use the net proceeds, if any, we receive from this offering, together with existing cash and cash equivalents, primarily to fund our research and development efforts, including Phase 2 clinical trials and potential commercialization of mecbotamab vedotin (BA3011), Phase 2 clinical trials of ozuriftamab vedotin (BA3021), clinical development of BA3071, preclinical development of several of our other CAB candidates, and for working capital and other general corporate purposes. This expected use of our net proceeds from this offering represents our intentions based upon our current plans and business conditions. The amount and timing of our actual expenditures may vary significantly depending on numerous factors, including the expenses related to our clinical and preclinical trials, the expenses related to any potential commercialization, as well as any strategic transactions that we may enter into with third parties, and any unforeseen cash needs. Because of the number and variability of factors that will determine our use of the proceeds from this offering, their ultimate use may vary substantially from their currently intended use. As a result, our management will retain broad discretion over the allocation of the net proceeds we receive from this offering and could spend the proceeds in ways that do not necessarily improve our financial condition or operating results or enhance the value of our common stock and your investment therein. Additionally, until the net proceeds we receive are used, they may be placed in investments that do not produce income or that lose value. See “Use of Proceeds” for additional information.

A significant portion of our total outstanding shares may be sold into the market at any time, which could cause the market price of our common stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. Such sales, or the perception in the market that the holders of a large number of such shares intend to sell, could reduce the market price of our common stock significantly.

Our stock price may be volatile, and you could lose all or part of your investment.

The trading price of our common stock has been and is likely to continue to be highly volatile. The market price for our common stock may be influenced by many factors, including the other risks described in this section and the following:

• the timing and results of our clinical trials or those of our competitors;

• regulatory or legal developments in the United States and other countries, especially changes in laws or regulations applicable to our products;

• the success of competitive products or technologies;

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• introductions and announcements of new products by us, our current or future collaborators or our competitors, and the timing of these introductions or announcements;

• announcements of new collaboration agreements, or the restructuring or termination of current collaboration agreements;

• actions taken by regulatory agencies with respect to our products, preclinical studies, clinical trials, manufacturing process or sales and marketing terms;

• actual or anticipated variations in our financial results or those of companies that are perceived to be similar to us;

• the success of our efforts to acquire or in-license additional technologies, products or product candidates;

• developments concerning any future collaborations, including those regarding manufacturing, supply and commercialization of our products;

• market conditions in the pharmaceutical and biotechnology sectors;

• announcements by us or our competitors of significant acquisitions, strategic collaborations, joint ventures or capital commitments;

• developments or disputes concerning patents or other proprietary rights, including patents, litigation matters and our ability to obtain patent protection for our products;

• our ability or inability to raise additional capital and the terms on which we raise it;

• the recruitment or departure of key personnel;

• changes in the structure of healthcare payment systems;

• actual or anticipated changes in earnings estimates or changes in stock market analyst recommendations regarding our common stock, other comparable companies or our industry generally;

• our failure or the failure of our competitors to meet analysts’ projections or guidance that we or our competitors may give to the market;

• fluctuations in the valuation of companies perceived by investors to be comparable to us;

• announcement and expectation of additional financing efforts;

• speculation in the press or investment community;

• trading volume of our common stock;

• sales of our common stock by us, our insiders or our other stockholders;

• expiration of market stand-off or lock-up agreements;

• the concentrated ownership of our common stock;

• changes in accounting principles;

• terrorist acts, acts of war or periods of widespread civil unrest;

• the impact of any natural disasters or public health emergencies, such as the COVID-19 pandemic; and

• general economic, industry and market conditions.

In addition, the stock markets in general, and the markets for pharmaceutical, biopharmaceutical and biotechnology stocks in particular, have experienced extreme volatility that has been often unrelated to the operating performance of the issuer. These broad market and industry factors may seriously harm the market price of our common stock, regardless of our operating performance.

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Future sales and issuances of our common stock or rights to purchase common stock, including pursuant to our equity incentive plans, could result in additional dilution of the percentage ownership of our stockholders and could cause our stock price to fall.

We may seek additional capital through a combination of public and private equity offerings, debt financings, strategic partnerships and alliances and licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms may include liquidation or other preferences that adversely affect your rights as a stockholder. The incurrence of indebtedness would result in increased fixed payment obligations and could involve certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. If we raise additional funds through strategic partnerships and alliances and licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies or product candidates, or grant licenses on terms unfavorable to us.

Sale of our common stock by existing stockholders, or the perception that these sales may occur, especially by directors, executive officers or significant stockholders of BioAtla, may cause our stock price to decline.

If our existing stockholders, in particular our directors, executive officers or other affiliates, sell substantial amounts of our common stock in the public market, or are perceived by the public market as intending to sell, the trading price of our common stock could decline. In addition, sales of these shares of common stock could impair our ability to raise capital, should we wish to do so. We cannot predict the timing or amount of future sales of our common stock by existing stockholders, but such sales, or the perception that such sales could occur, may adversely affect prevailing market prices for our common stock.

If securities or industry analysts do not publish research or reports about our business, or if they issue adverse or misleading research or reports regarding us, our business or our market, our stock price and trading volume could decline.

The trading market for our common stock is influenced by the research and reports that industry or securities analysts publish about us, our business or our market. If no or few securities or industry analysts commence or maintain coverage of us, the trading price for our stock would be negatively impacted. If any of the analysts who cover us issue adverse or misleading research or reports regarding us, our business model, our intellectual property, our stock performance or our market, or if our operating results fail to meet the expectations of analysts, our stock price would likely decline. If one or more of these analysts cease coverage of us or fail to publish reports on us regularly, we could lose visibility in the financial markets, which in turn could cause our stock price or trading volume to decline.

Because we do not anticipate paying any cash dividends on our capital stock in the foreseeable future, your ability to achieve a return on your investment will depend on appreciation of the value of our common stock.

We have never declared or paid cash dividends on our capital stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business and do not anticipate declaring or paying any cash dividends for the foreseeable future. Any return to stockholders will therefore be limited to any appreciation in the value of our common stock, which is not certain.

The shares of our common stock offered hereby will be sold in “at the market” offerings, and investors who buy shares of our common stock at different times will likely pay different prices.

Investors who purchase shares of our common stock in this offering at different times will likely pay different prices, and so may experience different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of shares of our common stock sold, and there is no minimum or maximum sales price for shares of our common stock to be sold in this offering. Investors may experience a decline in the value of their shares as a result of share sales made at prices lower than the prices they paid.

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The actual number of shares of our common stock that we will issue under the sales agreement, at any one time or in total, is uncertain.

Subject to certain limitations in the sales agreement and compliance with applicable law, we have the discretion to deliver placement notices to Jefferies at any time throughout the term of the sales agreement. The number of shares of our common stock that are sold by Jefferies after delivering a placement notice will fluctuate based on the market price of our common stock during the sales period and limits we set with Jefferies in any instruction to sell shares, and the demand for our common stock during the sales period. Because the price per share of each share of our common stock sold will fluctuate based on the market price of our common stock during the sales period, it is not possible at this stage to predict the number of shares of our common stock or the gross proceeds to be raised in connection with those sales, if any, that will be ultimately issued.

Changes in tax law may adversely affect us or our investors.

The rules dealing with U.S. federal, state and local income taxation are constantly under review by persons involved in the legislative process and by the Internal Revenue Service and the U.S. Treasury Department. Changes to tax laws (which changes may have retroactive application) could adversely affect us or holders of our common stock. In recent years, many such changes have been made and changes are likely to continue to occur in the future. Future changes in tax laws could have a material adverse effect on our business, cash flow, financial condition or results of operations. We urge investors to consult with their legal and tax advisers regarding the implications of potential changes in tax laws on an investment in our common stock.

Unstable market and economic conditions may have serious adverse consequences on our business, financial condition and stock price.

The global credit and financial markets have experienced extreme volatility and disruptions in the past several years, including severely diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates, rising inflation and interest rates, and uncertainty about economic stability. We believe that the state of global economic conditions is particularly volatile and uncertain due to recent and expected shifts in political, legislative and regulatory conditions concerning, among other matters, international trade and taxation, and that an uneven recovery or a renewed global downturn may negatively impact our ability to conduct clinical trials on the scale and timelines anticipated. There can be no assurance that further deterioration in credit and financial markets and confidence in economic conditions will not occur. Our general business strategy may be adversely affected by any such economic downturn, volatile business or political environment or continued unpredictable and unstable market conditions. If the current equity and credit markets deteriorate, it may make obtaining any necessary debt or equity financing more difficult, more costly and more dilutive. Failure to secure any necessary financing in a timely manner and on favorable terms could have a material adverse effect on our growth strategy, financial performance and stock price and could require us to delay or abandon clinical development plans. In addition, there is a risk that one or more of our current service providers, manufacturers and other partners may not survive an economic downturn, which could directly affect our ability to attain our operating goals on schedule and on budget. To the extent that our profitability and strategies are negatively affected by downturns or volatility in general economic conditions, our business and results of operations may be materially adversely affected.

We are a smaller reporting company, and we cannot be certain if the reduced reporting requirements applicable to smaller reporting companies will make our common stock less attractive to investors.

We are a “smaller reporting company” as defined in Rule 12b-2 promulgated under the Exchange Act. We may remain a smaller reporting company until we have a non-affiliate public float in excess of $250 million and annual revenues in excess of $100 million, or a non-affiliate public float in excess of $700 million, each as determined on an annual basis. A smaller reporting company may take advantage of relief from some of the reporting requirements and other burdens that are otherwise applicable generally to public companies. These provisions include: being permitted to provide only two years of audited financial statements, in addition to any

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required unaudited interim financial statements, with correspondingly reduced “Management’s Discussion and Analysis of Financial Condition and Results of Operations” disclosure; not being required to comply with the auditor attestation requirements in the assessment of our internal control over financial reporting; and reduced disclosure obligations regarding executive compensation in our periodic reports, proxy statements and registration statements. To the extent we take advantage of such scaled disclosures, it may also make comparison of our financial statements with other public companies difficult or impossible. We cannot predict if investors will find our common stock less attractive because we may take advantage of the scaled disclosures. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile.

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USE OF PROCEEDS

We may issue and sell shares of our common stock having aggregate sales proceeds of up to $100,000,000 from time to time. Because there is no minimum offering price for the shares that we may offer from time to time, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. There can be no assurance that we will sell any shares under or fully utilize the sales agreement with the sales agent as a source of financing.

Our management will have broad discretion over the uses of the net proceeds in this offering. We currently plan to use the net proceeds we receive from any sales of our common stock in this offering, if any, together with existing cash and cash equivalents, primarily to fund our research and development efforts, including Phase 2 clinical trials and potential commercialization of mecbotamab vedotin (BA3011), Phase 2 clinical trials of ozuriftamab vedotin (BA3021), clinical development of BA3071 and BA3182, preclinical development of several of our other CAB candidates, and for working capital and other general corporate purposes. We do not currently have specific plans or commitments with respect to the net proceeds from this offering and, accordingly, are not able to quantify the allocation of such proceeds among the various potential uses.

The amounts and timing of our actual expenditures will depend on numerous factors, including the progress of our clinical trials and other development efforts and other factors described under “Risk Factors” in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein, as well as the amount of cash used in our operations. We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the application of the net proceeds. Pending the uses described above, we plan to invest the net proceeds from this offering in short-term, interest-bearing accounts.

S-10

DIVIDEND POLICY

We have never declared or paid any cash dividends on our common stock to date. We currently intend to retain all available funds and any future earnings to support our operations and finance the growth and development of our business. We do not intend to pay cash dividends on our common stock for the foreseeable future. Any future determination related to our dividend policy will be made at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements, contractual restrictions, business prospects and other factors our board of directors may deem relevant.

S-11

PLAN OF DISTRIBUTION

We have entered into a sales agreement with Jefferies, under which we may offer and sell up to $100 million of our shares of common stock from time to time through Jefferies acting as agent. Sales of our shares of common stock, if any, under this prospectus supplement and the accompanying prospectus will be made by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act.

Each time we wish to issue and sell our shares of common stock under the sales agreement, we will notify Jefferies of the number of shares to be issued, the dates on which such sales are anticipated to be made, any limitation on the number of shares to be sold in any one day and any minimum price below which sales may not be made. Once we have so instructed Jefferies, unless Jefferies declines to accept the terms of such notice, Jefferies has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of Jefferies under the sales agreement to sell our shares of common stock are subject to a number of conditions that we must meet.

The settlement of sales of shares between us and Jefferies is generally anticipated to occur on the second trading day following the date on which the sale was made. Sales of our shares of common stock as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and Jefferies may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay Jefferies a commission equal to 3% of the aggregate gross proceeds we receive from each sale of our shares of common stock. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. In addition, we have agreed to reimburse Jefferies for the fees and disbursements of its counsel, payable upon execution of the sales agreement, in an amount not to exceed $75,000, in addition to certain ongoing disbursements of its legal counsel. We estimate that the total expenses for the offering, excluding any commissions or expense reimbursement payable to Jefferies under the terms of the sales agreement, will be approximately $350,000. The remaining sale proceeds, after deducting any other transaction fees, will equal our net proceeds from the sale of such shares.

Jefferies will provide written confirmation to us before the open on The Nasdaq Global Market on the day following each day on which our shares of common stock are sold under the sales agreement. Each confirmation will include the number of shares sold on that day, the aggregate gross proceeds of such sales and the proceeds to us.

In connection with the sale of our shares of common stock on our behalf, Jefferies may be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Jefferies will be deemed to be underwriting commissions or discounts. We have agreed to indemnify Jefferies against certain civil liabilities, including liabilities under the Securities Act. We have also agreed to contribute to payments Jefferies may be required to make in respect of such liabilities.

The offering of our shares of common stock pursuant to the sales agreement will terminate upon the earlier of (i) the sale of all shares of common stock subject to the sales agreement and (ii) the termination of the sales agreement as permitted therein. We and Jefferies may each terminate the sales agreement at any time upon ten trading days’ (as defined in the sales agreement) prior notice.

This summary of the material provisions of the sales agreement does not purport to be a complete statement of its terms and conditions. A copy of the sales agreement is filed as an exhibit to a current report on Form 8-K filed under the Exchange Act, and incorporated by reference in this prospectus supplement.

S-12

Jefferies and its affiliates may in the future provide various investment banking, commercial banking, financial advisory and other financial services for us and our affiliates, for which services they may in the future receive customary fees. In the course of its business, Jefferies may actively trade our securities for its own account or for the accounts of customers, and, accordingly, Jefferies may at any time hold long or short positions in such securities.

This prospectus supplement and the accompanying prospectus in electronic format may be made available on a website maintained by Jefferies, and Jefferies may distribute the prospectus supplement and the accompanying prospectus electronically.

S-13

LEGAL MATTERS

The validity of the shares of common stock offered by this prospectus supplement will be passed upon for the Company by Orrick, Herrington & Sutcliffe LLP. Cravath, Swaine & Moore LLP is acting as counsel for Jefferies LLC in connection with this offering.

S-14

EXPERTS

Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2021, and the effectiveness of our internal control over financial reporting as of December 31, 2021, as set forth in their reports, which are incorporated by reference in this prospectus supplement and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP’s reports, given on their authority as experts in accounting and auditing.

S-15

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to incorporate by reference the information and reports we file with it, which means that we can disclose important information to you by referring you to these documents. The information incorporated by reference is an important part of this prospectus, and the information that we file later with the SEC will automatically update and, where applicable, supersede the information already incorporated by reference. We are incorporating by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including all filings made after the date of the filing of this prospectus, except as to any portion of any future report or document that is not deemed filed under such provision, after the date of this prospectus and prior to the termination of this offering:

• Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on February 28, 2022;

• The information specifically incorporated by reference into our Annual Report on Form 10-K for the year ended December 31, 2021 from our definitive proxy statement on Schedule 14A, as filed with the SEC on  April 25, 2022;

• Quarterly Reports on Form 10-Q for the quarters ended March 31, 2022, June 30, 2022 and September 30, 2022, filed with the SEC on May 5, 2022, August 9, 2022 and  November 4, 2022, respectively;

• Current Reports on Form 8-K, filed with the SEC on  January 11, 2022,  February 25, 2022,  June 6, 2022,  June 17, 2022,  September  21, 2022, November  4, 2022 and November 7, 2022; and

• Description of our common stock contained in our registration statement on Form 8-A, dated December 9, 2020 as updated by the Description of the Registrant’s Securities Registered Pursuant to Section 12 of the Exchange Act, filed as Exhibit 4.3 to our Annual Report on Form 10-K for the year ended December 31, 2021, and including any amendment or report subsequently filed for the purpose of updating such description.

You may access our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, proxy statement, and other information, if any, we file with or furnish to the SEC free of charge at the SEC’s website (www.sec.gov) or our website (www.bioatla.com) as soon as reasonably practicable after such material is electronically filed with, or furnished to, the SEC. The information contained in, or that can be accessed through, our website is not part of this prospectus.

You may also request a copy of our SEC filings at no cost, by telephoning or writing us at the following telephone number or address:

BioAtla, Inc.

11085 Torreyana Road

San Diego, California 92121

Telephone: (858) 558-0708

S-16

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of the registration statement on Form S-3 we filed with the SEC under the Securities Act and does not contain all the information set forth or incorporated by reference in the registration statement. Whenever a reference is made in this prospectus to any of our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference into this prospectus for a copy of such contract, agreement or other document. Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public at the SEC’s website at http://www.sec.gov.

Our website address is www.bioatla.com. Through our website, we make available, free of charge, the following documents as soon as reasonably practicable after they are electronically filed with, or furnished to, the SEC, including our Annual Reports on Form 10-K; our proxy statements for our annual and special stockholder meetings; our Quarterly Reports on Form 10-Q; our Current Reports on Form 8-K; Forms 3, 4, and 5 with respect to our securities filed on behalf of our directors and our executive officers; and amendments to those documents. The information contained on, or that may be accessed through, our website or any of our social media channels is not a part of, and is not incorporated into, this prospectus.

S-17

PROSPECTUS

$200,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

From time to time, we may offer and sell up to $200,000,000 in the aggregate of any combination of the securities described in this prospectus in one or more offerings. The securities we may offer may be convertible into or exercisable or exchangeable for other securities. We may offer the securities separately or together, in separate classes, series and in amounts, at prices and on terms that will be determined at the time the securities are offered.

This prospectus describes some of the general terms that may apply to these securities. Each time securities are sold, the specific terms and amounts of the securities being offered, and any other information relating to the specific offering will be set forth in a supplement to this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before you invest in any of the securities being offered. This prospectus may not be used to sell our securities unless accompanied by a prospectus supplement.

Our common stock is traded on the Nasdaq Global Select Market under the symbol “BCAB”. On February 25, 2022, the closing price for our common stock, as reported on the Nasdaq Global Select Market, was $6.64 per share. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, of the securities covered by the applicable prospectus supplement.

We may offer and sell our securities to or through one or more underwriters, dealers and agents, or directly to purchasers, on an immediate, continuous or delayed basis. The names of any underwriters, dealers or agents and the terms of the arrangements with such entities will be stated in the accompanying prospectus supplement. See the sections of this prospectus entitled “About this Prospectus” and “Plan of Distribution” for more information.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties referenced under the heading “RISK FACTORS” on page 3 of this prospectus as well as those contained in the applicable prospectus supplement and any related free writing prospectus, and in the other documents that are incorporated by reference into this prospectus or the applicable prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is May 18, 2022.

TABLE OF CONTENTS

	Page
About This Prospectus		1
BioAtla, Inc		2
Risk Factors		3
Cautionary Statement Regarding Forward-Looking Statements		4
Use of Proceeds		5
Description of Our Capital Stock		6
Description of Our Debt Securities		11
Description of Our Warrants		12
Description of Our Units		13
Plan of Distribution		14
Legal Matters		15
Experts		15
Where You Can Find Additional Information		15
Incorporation of Certain Information by Reference		16

We are responsible for the information contained and incorporated by reference in this prospectus, in any accompanying prospectus supplement, and in any related free writing prospectus we prepare or authorize. We have not authorized anyone to give you any other information, and we take no responsibility for any other information that others may give you. If you are in a jurisdiction where offers to sell, or solicitations of offers to purchase, the securities offered by this documentation are unlawful, or if you are a person to whom it is unlawful to direct these types of activities, then the offer presented in this document does not extend to you. The information contained in this document speaks only as of the date of this document, unless the information specifically indicates that another date applies. Neither the delivery of this prospectus or any accompanying prospectus supplement, nor any sale of securities made under these documents, will, under any circumstances, create any implication that there has been no change in our affairs since the date of this prospectus, any accompanying prospectus supplement or any free writing prospectus we may provide you in connection with an offering or that the information contained or incorporated by reference is correct as of any time subsequent to the date of such information. You should assume that the information in this prospectus or any accompanying prospectus supplement, as well as the information incorporated by reference in this prospectus or any accompanying prospectus supplement, is accurate only as of the date of the documents containing the information, unless the information specifically indicates that another date applies. Our business, financial condition, results of operations and prospects may have changed since those dates.

i

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement we filed with the Securities and Exchange Commission (“SEC”), using a “shelf” registration process. Under this shelf registration process, we may sell any combination of the securities described in this prospectus from time to time in one or more offerings in an amount not to exceed $200,000,000 in the aggregate. Before purchasing any securities, you should read this prospectus and any applicable prospectus supplement together with the additional information described under the headings “Where You Can Find Additional Information” and “Incorporation of Certain Information by Reference.”

This prospectus only provides you with a general description of the securities we may offer. Each time we offer securities under this prospectus, we will provide a prospectus supplement that will contain more specific information about the terms of the offering, including, among other things, the specific amounts, prices and terms of the securities offered. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. This prospectus may not be used to sell our securities unless accompanied by a prospectus supplement. Each such prospectus supplement and any free writing prospectus that we may authorize to be provided to you may also add, update or change information contained in this prospectus or in documents incorporated by reference into this prospectus. If this prospectus is inconsistent with any prospectus supplement, you should rely upon the prospectus supplement.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information.”

This prospectus incorporates by reference, and any prospectus supplement or free writing prospectus may contain and incorporate by reference, market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information and we have not independently verified this information. In addition, the market and industry data and forecasts that may be included or incorporated by reference in this prospectus, any prospectus supplement or any applicable free writing prospectus may involve estimates, assumptions and other risks and uncertainties and are subject to change based on various factors, including those discussed under the heading “Risk Factors” contained in this prospectus, the applicable prospectus supplement and any applicable free writing prospectus, and under similar headings in other documents that are incorporated by reference into this prospectus. Accordingly, investors should not place undue reliance on this information.

Unless otherwise mentioned or unless the context requires otherwise, throughout this prospectus, any applicable prospectus supplement and any related free writing prospectus, the words “BioAtla”, “we”, “us”, “our”, the “company” or similar references refer to BioAtla, Inc.; and the term “securities” refers collectively to our common stock, preferred stock, warrants, debt securities, or any combination of the foregoing securities.

We have obtained a registered trademark for BioAtla^® in the United States. This prospectus and documents incorporated by reference into this prospectus contains references to our trademarks and to trademarks belonging to other entities. Solely for convenience, trademarks and trade names referred to in this prospectus and the documents incorporated by reference into this prospectus, including logos, artwork and other visual displays, may appear without the ^® or TM symbols, but such references are not intended to indicate, in any way, that we will not assert, to the fullest extent under applicable law, our rights or the rights of the applicable licensor to these trademarks and trade names. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

1

BIOATLA, INC.

We are a phase 2 clinical-stage biopharmaceutical company developing our novel class of highly specific and selective antibody-based therapeutics for the treatment of solid tumor cancer. Our CABs capitalize on our proprietary discoveries with respect to tumor biology, enabling us to target known and widely validated tumor antigens that have previously been difficult or impossible to target. Our novel CAB therapeutic candidates exploit characteristic pH differences between the tumor microenvironment and healthy tissue. Unlike healthy tissue, the tumor microenvironment is acidic, and we have designed our antibodies to selectively bind to their targets on tumor cells under acidic pH conditions but not on targets in normal tissues. Our approach is to identify the necessary targeting and potency required for cancer cell destruction, while aiming to eliminate or greatly reduce on-target, off-tumor toxicity—one of the fundamental challenges of existing cancer therapies.

We are a United States-based company with research facilities in San Diego, California and, through our contractual relationship with BioDuro-Sundia, a provider of preclinical development services, in Beijing, China. Since the commencement of our operations, we have focused substantially all of our resources on conducting research and development activities, including drug discovery, preclinical studies and clinical trials of our product candidates, including the ongoing Phase 2 clinical trials of BA3011 and BA3021, establishing and maintaining our intellectual property portfolio, manufacturing clinical and research material through third parties, hiring personnel, establishing product development and commercialization collaborations with third parties, raising capital and providing general and administrative support for these operations. Since 2014, such research and development activities have exclusively related to the research, development, manufacture and Phase 1 and Phase 2 clinical testing of our CAB antibody-based product candidates and the strengthening of our proprietary CAB technology platform and pipeline. We do not have any products approved for sale, and we have not generated any revenue from product sales.

CHANNELS FOR DISCLOSURE OF INFORMATION

Investors and others should note that we routinely announce material information to investors and the marketplace using filings with the SEC, press releases, public conference calls, presentations, webcasts and our investor relations website. While not all of the information that we post to our investor relations website is of a material nature, some information could be deemed to be material. Accordingly, we encourage investors, the media, and others interested in our company to review the information that we share at the “Investors” link located at the top of our webpage at www.ir.bioatla.com. Users may automatically receive email alerts and other information about our company when enrolling an email address by visiting Email Alerts in the Resources section of our website at https://ir.bioatla.com.

2

RISK FACTORS

Investing in our securities involves a high degree of risk. Before making a decision to invest in our securities, you should carefully consider the risks described under the heading “Risk Factors” in the applicable prospectus supplement and any related free writing prospectus, and discussed under “Part I, Item 1A. Risk Factors” contained in our most recent annual report on Form 10-K and in “Part II, Item 1A. Risk Factors” in our most recent quarterly report on Form 10-Q filed subsequent to such Form 10-K, as well as any amendments thereto, which are incorporated by reference into this prospectus and the applicable prospectus supplement in their entirety, together with other information in this prospectus and the applicable prospectus supplement, the documents incorporated by reference herein and therein, and any free writing prospectus that we may authorize for use in connection with a specific offering. See “Where You Can Find Additional Information.”

3

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any prospectus supplement and any related free writing prospectus, including the information incorporated by reference herein and therein, contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Any statements about our expectations, beliefs, plans, objectives, assumptions or future events or performance are not historical facts and may be forward-looking. These statements are often, but are not always, made through the use of words or phrases such as “anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “target,” “will,” “would,” or the negative of these words or other comparable terminology. Accordingly, these statements involve estimates, assumptions and uncertainties which could cause actual results to differ materially from those expressed in them.

Given these uncertainties, you should not place undue reliance on these forward-looking statements as actual events or results may differ materially from those projected in the forward-looking statements due to various factors, including, but not limited to, those set forth under the heading “Risk Factors” in any applicable prospectus supplement, the documents incorporated by reference therein or any free writing prospectus that we authorized. Our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements contained in this prospectus, in the documents incorporated by reference herein and in any prospectus supplement by these cautionary statements. These forward-looking statements speak only as of the date on which the statements were made and are not guarantees of future performance. Although we undertake no obligation to revise or update any forward-looking statements, whether as a result of new information, future events or otherwise, you are advised to review any additional disclosures we make in the documents we subsequently file with the SEC that are incorporated by reference in this prospectus and any prospectus supplement. See “Where You Can Find Additional Information.”

4

USE OF PROCEEDS

Unless otherwise indicated in a prospectus supplement, we intend to use the net proceeds from the sale of securities offered by this prospectus and any applicable prospectus supplement for general corporate purposes. Until we apply the proceeds from a sale of securities to their intended purposes, we may invest those proceeds in short-term, interest-bearing, investment-grade securities or hold as cash.

5

DESCRIPTION OF OUR CAPITAL STOCK

We have one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended: our common stock. The following summary of the terms of our common stock is based upon our restated certificate of incorporation and our restated bylaws. This summary does not purport to be complete and is subject to, and is qualified in its entirety by express reference to, the applicable provisions of our amended and restated certificate of incorporation and our amended and restated bylaws, which are filed as exhibits to our Annual Report on Form 10-K and are incorporated by reference herein. We encourage you to read our amended and restated certificate of incorporation, our amended and restated bylaws and the applicable provisions of the Delaware General Corporation Law for more information.

Common stock and class B common stock

We are authorized to issue up to a total of 350,000,000 shares of common stock, par value $0.0001 per share and up to a total of 15,368,569 shares of Class B common stock, par value $0.0001 per share. The holders of our common stock and Class B common stock have identical rights, provided that (i) except as otherwise expressly provided in our amended and restated certificate of incorporation or as required by applicable law, on any matter that is submitted to a vote by our stockholders, holders of our common stock are entitled to one vote per share of common stock, and holders of our Class B common stock are not entitled to any votes per share of Class B common stock, including for the election of directors and (ii) holders of our common stock have no conversion rights, while holders of our Class B common stock shall have the right to convert each share of our Class B common stock into one share of common stock at such holder’s election, provided that as a result of such conversion, such holder would not beneficially own in excess of 4.99% of any class of our securities registered under the Exchange Act, unless otherwise as expressly provided for in our amended and restated certificate of incorporation. However, this ownership limitation may be increased or decreased to any other percentage designated by such holder of Class B common stock upon 61 days’ notice to us.

Our common stock and Class B common stock have no preemptive rights or other subscription rights or redemption or sinking fund provisions. Upon our liquidation, dissolution or winding-up, holders of our common stock and Class B common stock are entitled to share ratably in all assets remaining after payment of all liabilities and the liquidation preferences of any of our outstanding shares of preferred stock. Subject to preferences that may be applicable to any outstanding shares of preferred stock, holders of our common stock and Class B common stock are entitled to receive dividends only if declared from time to time by our board of directors out of assets which are legally available.

Preferred stock

Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by the stockholders, to issue up to 200,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding.

Our board of directors may authorize the issuance of preferred stock with voting or conversion rights that could adversely affect the voting power or other rights of the holders of the common stock. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could, among other things, have the effect of delaying, deferring or preventing a change in our control that may otherwise benefit holders of our common stock and may adversely affect the market price of the common stock and the voting and other rights of the holders of common stock.

Warrants

As of December 31, 2021, we had 151,088 outstanding warrants.

6

On June 6, 2016, we issued warrants to purchase an aggregate of 151,088 shares of common stock at an exercise price of $132.37 per share, which warrants were subsequently amended and restated. The warrants are exercisable during the period commencing on December 19, 2020 and ending on March 13, 2022, and provide for cashless exercise at the option of the warrant holder.

Registration rights

As of the completion of the initial public offering and subject to the lock-up agreements entered into in connection with such offering and federal securities laws, certain holders of shares of our common stock are entitled to certain rights with respect to registration of such shares under the Securities Act. These shares are referred to as registrable securities. The registration of shares of our common stock pursuant to the exercise of the registration rights described below would enable the holders to trade these shares without restriction under the Securities Act when the applicable registration statement is declared effective. We will pay the registration expenses, other than underwriting discounts, selling commissions and stock transfer taxes, of the shares registered pursuant to the demand, piggyback and Form S-3 registrations described below.

Generally, in an underwritten offering, the managing underwriter, if any, has the right, subject to specified conditions and limitations, to limit the number of shares the holders may include. The demand, piggyback and Form S-3 registration rights described below will terminate upon the earliest of (i) with respect to each stockholder, such date, on or after the completion of our initial public offering, on which all registrable shares held by such stockholder may immediately be sold during any three month period pursuant to Rule 144, (ii) the occurrence of a deemed liquidation event, as defined in our certificate of incorporation, as currently in effect and (iii) the fifth anniversary of the completion of our initial public offering.

Demand registration rights

As of December 31, 2021, certain holders of shares of our common stock are entitled to certain demand registration rights. Investors holding, collectively, a majority of registrable securities having an anticipated aggregate offering price of at least $5.0 million may, on not more than two occasions, request that we register all or a portion of their shares, subject to certain specified exceptions. If any of these holders exercises its demand registration rights, then certain holders of shares of our common stock will be entitled to register their shares, subject to specified conditions and limitations in the corresponding offering.

Piggyback registration rights

As of December 31, 2021, certain holders of shares of our common stock are entitled to their rights to notice of public offerings and to include their shares of registrable securities in public offerings. In the event that we propose to register any of our securities under the Securities Act in an offering, either for our own account or for the account of other security holders, the holders of registrable securities will be entitled to certain “piggyback” registration rights allowing them to include their shares in such registration, subject to specified conditions and limitations.

S-3 registration rights

As of December 31, 2021, certain holders of shares of our common stock are initially entitled to certain Form S-3 registration rights. Certain major investors holding at least 10% of registrable securities may, on not more than two registrations on Form S-3 within any 12-month period, request that we register all or a portion of their shares on Form S-3 if we are qualified to file a registration statement on Form S-3, subject to specified exceptions. Such request for registration on Form S-3 must cover securities with an aggregate offering price which equals or exceeds $3.0 million, net of selling expenses. The right to have such shares registered on Form S-3 is further subject to other specified conditions and limitations.

7

Anti-takeover effects of provisions of our certificate of incorporation, our bylaws and Delaware law

Certain provisions of Delaware law and certain provisions included in our amended and restated certificate of incorporation and amended and restated bylaws, summarized below, may be deemed to have an anti-takeover effect and may delay or discourage transactions involving an actual or potential change in our control or change in our management, including transactions in which stockholders might otherwise receive a premium for their shares or transactions that our stockholders might otherwise deem to be in their best interests. Therefore, these provisions could adversely affect the price of our common stock.

Delaware anti-takeover law

We are subject to Section 203 of the Delaware General Corporation Law, or Section 203. Section 203 generally prohibits a public Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years after the date of the transaction in which the person became an interested stockholder, unless:

• prior to the date of the transaction, the board of directors of the corporation approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder;

• the interested stockholder owned at least 85% of the voting stock of the corporation outstanding upon consummation of the transaction, excluding for purposes of determining the number of shares outstanding (a) shares owned by persons who are directors and also officers and (b) shares owned by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or

• on or subsequent to the consummation of the transaction, the business combination is approved by the board and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least 66 2/3% of the outstanding voting stock which is not owned by the interested stockholder.

Section 203 defines a business combination to include:

• any merger or consolidation involving the corporation and the interested stockholder;

• any sale, transfer, pledge or other disposition involving the interested stockholder of 10% or more of the assets of the corporation;

• subject to exceptions, any transaction involving the corporation that has the effect of increasing the proportionate share of the stock of any class or series of the corporation beneficially owned by the interested stockholder;

• subject to exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder; and

• the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits provided by or through the corporation.

In general, Section 203 defines an interested stockholder as any entity or person beneficially owning 15% or more of the outstanding voting stock of the corporation and any entity or person affiliated with or controlling or controlled by the entity or person.

Preferred stock

Our amended and restated certificate of incorporation contains provisions that permit our board of directors to issue, without any further vote or action by the stockholders, shares of preferred stock in one or more series and, with respect to each such series, to fix the number of shares constituting the series and the designation of the

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series, the voting rights (if any) of the shares of the series and the powers, preferences or relative, participation, optional and other special rights, if any, and any qualifications, limitations or restrictions, of the shares of such series.

Classified board

Our amended and restated certificate of incorporation provides that our board of directors is divided into three classes, designated Class I, Class II and Class III. Each class will be an equal number of directors, as nearly as possible, consisting of one third of the total number of directors constituting the entire board of directors.

Removal of directors

Our amended and restated certificate of incorporation provides that stockholders may only remove a director for cause by a vote of at least 66 2/3% of the voting power of all of our then outstanding common stock and that the authorized number of directors may be changed only by resolution adopted by a majority of the board of directors.

Director vacancies

Our amended and restated certificate of incorporation provides that all vacancies, including newly created directorships, may, except as otherwise required by law or subject to the rights of holders of preferred stock as designated from time to time, be filled by the affirmative vote of a majority of directors then in office, even if less than a quorum.

Special meetings of stockholders

Our amended and restated certificate of incorporation and our amended and restated bylaws provide that, except as otherwise required by law, special meetings of our stockholders may be called only by the chairman of the board, our Chief Executive Officer or by the board of directors pursuant to a resolution adopted by a majority of the total number of authorized directors (whether or not there exists any vacancies).

Advance notice procedures for director nominations

Our amended and restated certificate of incorporation and amended and restated bylaws provide that stockholders seeking to nominate candidates for election as directors at an annual or special meeting of stockholders must provide timely notice thereof in writing and also specify requirements as to the form and content of a stockholder’s notice.

Action by written consent

Our amended and restated certificate of incorporation and amended and restated bylaws require that any action to be taken by our stockholders must be effected at a duly called annual or special meeting of stockholders and not be taken by written consent.

Cumulative voting

Our amended and restated certificate of incorporation provides for cumulative voting rights (therefore allowing the holders of a majority of the shares of common stock entitled to vote in any election of directors to elect all of the directors standing for election, if they should so choose).

Amending our certificate of incorporation and bylaws

The amendment of any of the provisions in our amended and restated certificate of incorporation, with the exception of the ability of our board of directors to issue shares of preferred stock and designate any rights, preferences and privileges thereto, would require the affirmative vote of the holders of at least 66 2/3% of the

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voting power of all of our then outstanding common stock. Additionally, our amended and restated certificate of incorporation provides that our bylaws may be amended, altered or repealed by the board of directors.

Exclusive forum provision

Our amended and restated certificate of incorporation provides that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware (or, if the Court of Chancery of the State of Delaware does not have jurisdiction, the federal district court for the District of Delaware) shall be the sole and exclusive forum for the following types of proceedings: (i) any derivative action or proceeding brought on behalf of our company, (ii) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers, employees or stockholders to our company or our stockholders, (iii) any action asserting a claim arising pursuant to any provision of the General Corporation Law of the State of Delaware or as to which the General Corporation Law of the State of Delaware confers jurisdiction on the Court of Chancery of the State of Delaware or (iv) any action asserting a claim arising pursuant to any provision of our amended and restated certificate of incorporation or amended and restated bylaws (in each case, as they may be amended from time to time) or governed by the internal affairs doctrine. This provision would not apply to suits brought to enforce a duty or liability created by the Exchange Act or any other claim for which the U.S. federal courts have exclusive jurisdiction. Furthermore, Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all such Securities Act actions. Accordingly, both state and federal courts have jurisdiction to entertain such claims. Our amended and restated bylaws further provide that the federal district courts of the United States of America will be the exclusive forum to the fullest extent permitted by law, for resolving any complaint asserting a cause of action arising under the Securities Act. This choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers or other employees, which may discourage such lawsuits against us and our directors, officers and employees. Alternatively, if a court were to find these provisions of our amended and restated certificate of incorporation and amended and restated bylaws inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings, we may incur additional costs associated with resolving such matters in other jurisdictions, which could adversely affect our business and financial condition. Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock shall be deemed to have notice of and to have consented to the provisions of our amended and restated certificate of incorporation and amended and restated bylaws described above.

Nasdaq Global Market

Our common stock is listed on The Nasdaq Global Market under the symbol “BCAB.”

Transfer agent and registrar

The transfer agent and registrar for our common stock and Class B common stock is Philadelphia Stock Transfer, Inc. The transfer agent and registrar’s address is 2320 Haverford Rd., Suite 230, Ardmore, PA 19003.

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DESCRIPTION OF OUR DEBT SECURITIES

The debt securities will constitute either senior or subordinated debt of BioAtla, Inc. The debt securities that are sold may be exchangeable for and/or convertible into shares of common stock or any of the other securities that may be sold under this prospectus. The debt securities will be issued under one or more separate indentures between us and a designated trustee. We will include in a prospectus supplement the specific terms of each series of senior or subordinated debt securities being offered, including the terms, if any, on which a series of senior or subordinated debt securities may be convertible into or exchangeable for other securities. In addition, the material terms of any indenture, which will govern the rights of the holders of our senior or subordinated debt securities will be set forth in the applicable prospectus supplement.

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DESCRIPTION OF OUR WARRANTS

We may issue warrants to purchase our debt or equity securities or securities of third parties or other rights, including rights to receive payment in cash or securities based on the value, rate or price of one or more specified commodities, currencies, securities or indices, or any combination of the foregoing. Warrants may be issued independently or together with any other securities and may be attached to, or separate from, such securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and a warrant agent. The terms of any warrants to be issued and a description of the material provisions of the applicable warrant agreement will be set forth in the applicable prospectus supplement.

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DESCRIPTION OF OUR UNITS

As specified in the applicable prospectus supplement, we may issue units consisting of one or more shares of common stock, shares of preferred stock, debt securities or warrants or any combination of such securities.

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PLAN OF DISTRIBUTION

We may offer and sell the securities being offered hereby in one or more of the following ways from time to time:

• to or through underwriters;

• on any national securities exchange or quotation service on which the securities may be listed or quoted at the time of sale;

• in the over-the-counter market;

• in transactions other than on these exchanges or systems or in the over-the-counter market;

• in “at the market offerings,” within the meaning of Rule 415(a)(4) of the Securities Act, to or through market makers or into an existing market for the securities;

• through the writing or settlement of options or other hedging transactions, whether through an options exchange or otherwise;

• ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

• block trades in which the broker-dealer will attempt to sell the shares as agent but may position and resell a portion of the block as principal to facilitate the transaction;

• purchases by a broker-dealer as principal and resale by the broker-dealer for its account;

• an exchange distribution in accordance with the rules of the applicable exchange;

• privately negotiated transactions;

• a combination of any of these methods of sale; and

• any other method permitted pursuant to applicable law.

We will identify the specific plan of distribution, including any underwriters, dealers, agents or other purchasers, persons or entities, and any applicable compensation, in a prospectus supplement, in an amendment to the registration statement of which this prospectus is a part, or in other filings we make with the SEC under the Exchange Act, which are incorporated by reference.

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LEGAL MATTERS

Unless the applicable prospectus supplement indicates otherwise, the validity of the securities being offered by this prospectus will be passed upon by Orrick, Herrington & Sutcliffe LLP, San Francisco, California. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2021, and the effectiveness of our internal control over financial reporting as of December 31, 2021, as set forth in their reports, which are incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP’s reports, given on their authority as experts in accounting and auditing.

WHERE YOU CAN FIND ADDITIONAL INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public at the SEC’s website at www.sec.gov.

We have filed with the SEC a registration statement on Form S-3 relating to the securities covered by this prospectus. This prospectus is a part of the registration statement and does not contain all the information in the registration statement. Other documents establishing the terms of the offered securities are or may be filed as exhibits to the registration statement or documents incorporated by reference in the registration statement. Whenever a reference is made in this prospectus to a contract or other document of ours, the reference is only a summary and you should refer to the exhibits that are a part of the registration statement for a copy of the contract or other document. You may review a copy of the registration statement through the SEC’s website, as provided above.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” the information from other documents we file with the SEC, which means that we can disclose important information to you by referring you to those documents instead of having to repeat the information in this prospectus. The information incorporated by reference is considered to be part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act on or after the date of this prospectus (other than, in each case, documents or information deemed to have been furnished and not filed in accordance with SEC rules) until the termination of the registration statement of which this prospectus is a part:

• Our Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on February 28, 2022;

• Our Current Reports on Form 8-K filed with the SEC on January 11, 2022 and February 25, 2022; and

• The description of our common stock contained in the Registration Statement on Form 8-A filed with the SEC on December 9, 2020, including any amendment or report filed for the purpose of updating such description.

Any statement contained in this prospectus, or in a document all or a portion of which is incorporated by reference, shall be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus, any applicable prospectus supplement and any related free writing prospectus or any document incorporated by reference modifies or supersedes such statement. Any such statement so modified or superseded shall not, except as so modified or superseded, constitute a part of this prospectus.

Upon request, we will provide, without charge, to each person, including any beneficial owner, to whom a copy of this prospectus is delivered a copy of the documents incorporated by reference into this prospectus. You may request a copy of these filings, and any exhibits we have specifically incorporated by reference as an exhibit in this prospectus, at no cost by writing or telephoning us at the following:

BioAtla, Inc.

11085 Torreyana Road

San Diego, California 92121

(858) 558-0708

Attn: Investor Relations

You may also access these documents, free of charge on the SEC’s website at www.sec.gov or on the “Investor Relations” page of our website at www.ir.bioatla.com. Information contained on our website is not incorporated by reference into this prospectus, and you should not consider any information on, or that can be accessed from, our website as part of this prospectus or any accompanying prospectus supplement.

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$100,000,000

Common Stock

PROSPECTUS SUPPLEMENT

Jefferies

January 6, 2023