[Form 3/A] SUTRO BIOPHARMA, INC. Amended Initial Statement of Beneficial Ownership

Rhea-AI Filing Summary

David Pauling, Chief Administrative Officer and General Counsel of Sutro BioPharma, Inc. (STRO), amended his Form 3 to correct the number of shares he beneficially owns. The filing reports 56,733 shares of common stock held directly. The amendment notes the original Form 3 filed on April 8, 2025 misstated the total and is otherwise unchanged. The event date requiring the statement is 04/04/2025, and the amended Form 3/A is signed by Mr. Pauling on 09/12/2025.

Positive

• Disclosure corrected to reflect accurate insider holdings, improving transparency
• Reporting officer identified with title (Chief Administrative Officer & General Counsel), clarifying role and relationship to issuer

Negative

• Initial misstatement in the original Form 3 required an amendment
• No information provided about why the original number was misstated beyond describing it as inadvertent

Insights

Corporate Governance Expert

TL;DR: Routine corrective amendment that restores accurate public disclosure of insider holdings.

This amendment corrects the reported number of common shares held by a senior executive, aligning public records with the reporting person's actual holdings. Accurate Section 16 reporting is important for transparency and compliance; the amendment indicates the company and officer are rectifying an inadvertent misstatement rather than disclosing a new transaction. The disclosure does not include derivative positions or changes in ownership form, and no additional material corporate actions are reported.

Securities Analyst

TL;DR: Administrative correction with no apparent impact on capitalization or control.

The filing shows 56,733 shares held directly by an officer. There is no indication of recent purchases, sales, options, or other derivative instruments in this amendment. From an investor-impact perspective, this is a compliance update that does not alter outstanding share counts reported by the issuer or imply a change in insider conviction.

SEC Form 3

FORM 3

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

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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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1. Name and Address of Reporting Person^*

Pauling David

(Last) (First) (Middle)

C/O SUTRO BIOPHARMA, INC.

111 OYSTER POINT BLVD.

(Street)

SOUTH SAN FRANCISCO CA 94080

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
04/04/2025

3. Issuer Name and Ticker or Trading Symbol
SUTRO BIOPHARMA, INC. [ STRO ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Admin. Ofcr. & GC

5. If Amendment, Date of Original Filed (Month/Day/Year)
04/08/2025

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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	56,733(1)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The reporting person's Form 3 filed on April 8, 2025 is being amended herein to correct the number of shares of Common Stock beneficially owned, which was inadvertently misstated in the original filing.

Remarks:

The reporting person's Form 3 filed on April 8, 2025 is amended hereby solely to correct the total securities reported as beneficially owned in Column 2 of Table I. The original Form 3 and Power of Attorney filed as Exhibit 24.1 thereto remain otherwise unmodified.

	/s/ David Pauling	09/12/2025
	** 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 5 (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 the Form 3/A filed by David Pauling disclose about STRO holdings?

The amendment reports 56,733 shares of Sutro BioPharma, Inc. (STRO) common stock beneficially owned directly by David Pauling.

Why was the Form 3 amended for STRO?

The Form 3/A amends the original filing to correct the number of shares

Does the amendment report any derivative securities or transactions for STRO?

No. The amendment lists only non-derivative common stock holdings and does not report any options, warrants, or other derivative securities.

When is the event date requiring this filing for STRO?

The event date requiring the statement is 04/04/2025.

When was the amended Form 3/A signed?

The amended Form 3/A is signed by David Pauling on 09/12/2025.