BioAtla (BCAB) CMO reports 3,140-share tax withholding on RSU vesting

Rhea-AI Filing Summary

BioAtla, Inc. reported an insider equity transaction for Chief Medical Officer Eric Sievers. On this Form 4, the company withheld 3,140 shares of common stock at $0.247 per share to satisfy income tax and withholding obligations related to the vesting of previously reported restricted stock units. This withholding is characterized as a tax-withholding disposition and is explicitly noted as not being a sale of shares by the reporting person. After this transaction, Sievers directly held 358,705 shares of BioAtla common stock.

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

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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 CA 92121

(City) (State) (Zip)

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

3. Date of Earliest Transaction (Month/Day/Year)
02/28/2026

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

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

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

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/28/2026		F(1)		3,140	D	$0.247	358,705	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

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.

	Christian Vasquez, as Attorney-in-Fact for Eric Sievers	03/02/2026
	** 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).
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FAQ

What insider transaction did BioAtla (BCAB) report for Eric Sievers?

BioAtla reported that Chief Medical Officer Eric Sievers had 3,140 common shares withheld to cover tax obligations from vesting restricted stock units. The shares were valued at $0.247 each, and the filing clarifies this was not an open-market sale by Sievers.

Was the BioAtla (BCAB) Form 4 transaction a sale of shares?

No, the filing states the transaction was not a sale by Eric Sievers. Instead, BioAtla withheld 3,140 common shares to satisfy income tax, withholding, and remittance obligations tied to the vesting and net settlement of previously reported restricted stock units.

How many BioAtla (BCAB) shares were withheld for taxes in this Form 4?

The Form 4 shows that 3,140 shares of BioAtla common stock were withheld. These shares covered income tax and withholding obligations triggered by the vesting of restricted stock units, rather than representing a discretionary sale or purchase in the open market by the executive.

What price per share is shown in the BioAtla (BCAB) Form 4 transaction?

The Form 4 reports a transaction price of $0.247 per share for the 3,140 BioAtla common shares withheld. This figure is used in connection with the tax-withholding disposition arising from the vesting and net settlement of previously reported restricted stock units for the executive.

How many BioAtla (BCAB) shares does Eric Sievers hold after the Form 4 event?

After the tax-withholding disposition, Eric Sievers directly holds 358,705 shares of BioAtla common stock. This post-transaction balance reflects the net position following the withholding of 3,140 shares to satisfy income tax and related withholding obligations tied to restricted stock unit vesting.

What does transaction code F mean in the BioAtla (BCAB) Form 4?

Transaction code F indicates a tax-related disposition, where shares are delivered or withheld to pay an exercise price or tax liability. In this case, 3,140 BioAtla shares were withheld by the issuer to meet income tax and withholding obligations from restricted stock unit vesting.