What is the significance of BioAtla’s 50-for-1 share consolidation mentioned in the Form 4?

BioAtla implemented a 50-for-1 share consolidation effective April 6, 2026. The Form 4 notes that all reported share amounts for Eric Sievers’ transactions and holdings have been adjusted to reflect this consolidation, changing the share counts but not the underlying economic value.

BioAtla (BCAB) CMO has 494 shares withheld to cover RSU taxes

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

BioAtla, Inc. Chief Medical Officer Eric Sievers reported routine tax-related share withholdings, not open-market sales. On two dates, a total of 494 common shares were withheld by the company to satisfy income tax obligations tied to vested restricted stock units. Following the most recent withholding, Sievers directly owned 11,840 common shares. The reported amounts have been adjusted to reflect a 50-for-1 share consolidation effective on April 6, 2026.

Insider Trade Summary

2 transactions reported

Mixed 2 txns

Insider Sievers Eric

Role Chief Medical Officer

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	134	$3.93	$526.62
Tax Withholding	Common Stock	360	$0.169	$60.84

Holdings After Transaction: Common Stock — 11,840 shares (Direct, null)

Footnotes (1)

This transaction is not a sale of shares by the Reporting Person. Instead, this represents shares that have been withheld by the Issuer to satisfy its income tax and withholding and remittance obligations in connection with the vesting and net settlement of previously reported restricted stock units. Effective on April 6, 2026, the Issuer effected a 50-for-1 share consolidation of its common stock (the "Share Consolidation"). The amount of securities reported on this Form 4 has been adjusted to reflect the Share Consolidation.

Key Figures

Tax-withheld shares total: 494 shares Shares withheld on 2026-05-31: 134 shares at $3.93/share Shares withheld on 2026-03-11: 360 shares at $0.169/share +3 more

6 metrics

Tax-withheld shares total 494 shares Common stock withheld to cover income tax obligations

Shares withheld on 2026-05-31 134 shares at $3.93/share Tax-withholding disposition of common stock

Shares withheld on 2026-03-11 360 shares at $0.169/share Tax-withholding disposition of common stock

Shares owned after latest transaction 11,840 shares Direct common stock ownership after 2026-05-31 withholding

Share consolidation ratio 50-for-1 Common stock share consolidation effective April 6, 2026

Tax-withholding transactions count 2 transactions Both reported as code F tax-withholding dispositions

Key Terms

restricted stock units, share consolidation, tax-withholding disposition, payment of exercise price or tax liability by delivering securities

4 terms

restricted stock units financial

"in connection with the vesting and net settlement of previously reported restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax-withholding disposition financial

"transaction_action": "tax-withholding disposition""

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

payment of exercise price or tax liability by delivering securities financial

"transaction_code_description": "Payment of exercise price or tax liability by delivering securities""

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Form 4 Insider Transactions: What Each Field Means →

06/05/2026 - 04:30 PM

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Sievers Eric

(Last)

(First)

(Middle)

C/O BIOATLA, INC. 11085 TORREYANA ROAD

(Street)

SAN DIEGO

CALIFORNIA

92121

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
BioAtla, Inc. [ BCAB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	Chief Medical Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/11/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	03/11/2026		F⁽¹⁾		360	D	$0.169	11,614⁽²⁾	D
Common Stock	05/31/2026		F⁽¹⁾		134	D	$3.93	11,840⁽²⁾	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. This transaction is not a sale of shares by the Reporting Person. Instead, this represents shares that have been withheld by the Issuer to satisfy its income tax and withholding and remittance obligations in connection with the vesting and net settlement of previously reported restricted stock units.

2. Effective on April 6, 2026, the Issuer effected a 50-for-1 share consolidation of its common stock (the "Share Consolidation"). The amount of securities reported on this Form 4 has been adjusted to reflect the Share Consolidation.

	Christian Vasquez, as Attorney-in-Fact for Eric Sievers	06/05/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What did BioAtla (BCAB) Chief Medical Officer Eric Sievers report in this Form 4?

Eric Sievers reported tax-related share withholdings, not market sales. BioAtla withheld common shares to cover income tax obligations from vesting restricted stock units, and these transactions adjusted his direct holdings without reflecting discretionary buying or selling in the open market.

How many BioAtla (BCAB) shares were withheld for taxes in Sievers’ transactions?

A total of 494 common shares were withheld to cover taxes. One transaction involved 134 shares at $3.93 per share, and another involved 360 shares at $0.169 per share, both designated as tax-withholding dispositions related to restricted stock unit vesting.

Were Sievers’ BioAtla (BCAB) transactions open-market sales of stock?

The transactions were not open-market sales. Footnotes state the shares were withheld by BioAtla to satisfy income tax and withholding obligations on vesting restricted stock units, meaning the company retained shares rather than Sievers actively selling them into the market.

How many BioAtla (BCAB) shares does Eric Sievers own after the latest Form 4 transaction?

After the most recent tax-withholding disposition, Sievers directly owns 11,840 common shares. This figure reflects adjustments for the 50-for-1 share consolidation effective April 6, 2026, as noted in the Form 4 footnotes for all reported amounts.

How are Sievers’ BioAtla (BCAB) Form 4 transactions classified by the SEC codes?

Both transactions use code F, indicating payment of tax liability by delivering securities. They are classified as tax-withholding dispositions of common stock, not as open-market purchases or sales, and are tied to the vesting and settlement of previously reported restricted stock units.