[Form 4] BioAtla, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Eric Sievers, Chief Medical Officer of BioAtla, Inc. (BCAB), reported a withholding transaction tied to vested restricted stock units. On 08/31/2025, 2,729 shares were withheld at an effective price of $0.4555 to satisfy income tax and withholding obligations related to prior RSU vesting. After the withholding, the filing shows 364,574 shares beneficially owned by Sievers. The Form 4 was signed by an attorney-in-fact on 09/02/2025. The filing explicitly states this was a net settlement withholding, not an open-market sale.

Positive

• Clear disclosure of the withholding transaction and its purpose (tax and remittance on vested RSUs).
• Compliance with Section 16 reporting shown by timely Form 4 submission and explanatory note.

Negative

• None.

Insights

Financial Analyst

TL;DR: Routine insider withholding for taxes on vested RSUs; no sale proceeds and limited market impact.

This Form 4 documents a tax-withholding net settlement of previously granted restricted stock units. The withheld amount, 2,729 shares at $0.4555, reduces the reporting person’s post-transaction share count to 364,574. Because shares were withheld rather than sold on the open market, there is no direct change in share supply from a sale event. The disclosure complies with Section 16 reporting requirements and provides transparency on insider equity changes.

Corporate Governance Expert

TL;DR: Standard compliance disclosure reflecting executive tax withholding on vested equity; governance signals are routine.

The filing indicates appropriate reporting of equity compensation settlement mechanics. Net settlement to cover tax obligations is a common mechanism for RSUs and the form clarifies the nature of the transaction. The signature by an attorney-in-fact is noted, and the explanation field clearly states the transaction was not a sale by the reporting person, which maintains clarity for shareholders reviewing insider activity.

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)
08/31/2025

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	08/31/2025		F(1)		2,729	D	$0.4555	364,574	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.

	/s/ Christian Vasquez, as Attorney-in-Fact for Eric Sievers	09/02/2025
	** 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.

FAQ

What did Eric Sievers report on Form 4 for BCAB?

He reported a net settlement withholding of 2,729 shares on 08/31/2025 related to vested restricted stock units.

Was the transaction a market sale of BCAB shares?

No. The filing states the shares were withheld by the issuer to satisfy tax and withholding obligations, not sold in the market.

How many BCAB shares does Eric Sievers beneficially own after the transaction?

The Form 4 reports 364,574 shares beneficially owned following the withholding.

At what price were the withheld BCAB shares recorded?

The withheld shares are shown at a price of $0.4555 per share.

Who signed the Form 4 filing for Eric Sievers and when?

The form was signed by Christian Vasquez, as Attorney-in-Fact for Eric Sievers on 09/02/2025.