BioAtla CMO has 134 shares withheld for taxes

BioAtla’s chief medical officer had a small number of shares withheld for tax obligations tied to RSU vesting, leaving him with 11,346 directly held shares.

Rhea-AI Filing Summary

BioAtla, Inc. (BCAB) reported that Chief Medical Officer Eric Sievers had 134 shares of common stock withheld on August 31, 2026 to satisfy income tax and withholding obligations related to the vesting and net settlement of previously reported restricted stock units. This was not an open-market sale, and he beneficially holds 11,346 shares directly after the transaction. No transactions were made under a Rule 10b5-1 trading plan.

Insider Trade Summary

Tax Withholding: 134 shares

Tax Withholding 1 txn

Insider Sievers Eric

Role Chief Medical Officer

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock F1	134	$1.69	$226.46

Holdings After Transaction: Common Stock — 11,346 shares (Direct)

Footnotes (1)

1. F1. 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.

Key Figures

Shares withheld for tax obligations: 134 shares Withholding price per share: $1.69 per share Shares held after transaction: 11,346 shares

3 metrics

Shares withheld for tax obligations 134 shares Common stock withheld on August 31, 2026 to satisfy tax and withholding obligations on RSU vesting

Withholding price per share $1.69 per share Value applied to the 134 withheld shares on August 31, 2026

Shares held after transaction 11,346 shares Directly held BioAtla common stock by Eric Sievers following the August 31, 2026 withholding

Key Terms

restricted stock units, net settlement, withheld by the Issuer, income tax and withholding and remittance obligations

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.

net settlement financial

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

withheld by the Issuer financial

"represents shares that have been withheld by the Issuer to satisfy its income tax"

income tax and withholding and remittance obligations financial

"to satisfy its income tax and withholding and remittance obligations in connection"

FAQ

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

BioAtla disclosed that Chief Medical Officer Eric Sievers had 134 shares of common stock withheld on August 31, 2026 to cover income tax and withholding obligations arising from the vesting and net settlement of previously reported restricted stock units.

Was the August 31, 2026 BCAB transaction a market sale of shares?

No. The filing states the transaction is not a sale of shares by Eric Sievers. The 134 shares were withheld by BioAtla to satisfy income tax, withholding, and remittance obligations related to vested restricted stock units.

How many BioAtla (BCAB) shares does Eric Sievers hold after this Form 4 transaction?

After the August 31, 2026 withholding transaction, Eric Sievers directly holds 11,346 shares of BioAtla common stock, according to the reported post-transaction ownership figure on the Form 4.

At what price were the withheld BioAtla (BCAB) shares valued in this Form 4?

The 134 shares withheld to satisfy tax obligations were valued at a price of $1.69 per share, which the Form 4 reports as the transaction price for the common stock on August 31, 2026.

Was a Rule 10b5-1 trading plan involved in this BioAtla (BCAB) Form 4 transaction?

No. The Form 4 indicates no Rule 10b5-1 trading plan for this transaction; the document-level checkbox for such a plan is not checked, and the footnote describes only tax-withholding related to RSU vesting.

What security type is involved in Eric Sievers’ August 31, 2026 BCAB Form 4?

The transaction involves BioAtla common stock. The shares were withheld in connection with the net settlement of previously reported restricted stock units that vested, creating a tax obligation.

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Available on EDGAR 09/02/2026 - 05:29 PM Accepted by SEC EDGAR 09/02/2026 - 05:28 PM Learn about SEC filing dates

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)
08/31/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/31/2026		F(1)		134	D	$1.69	11,346	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	09/02/2026
	** 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).
** 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)