Penumbra (PEN) CAO Lambert Shiu reports 150-share tax withholding event

Rhea-AI Filing Summary

Penumbra Inc’s Chief Accounting Officer Lambert Shiu reported a routine tax-related share disposition. On March 15, 2026, 150 shares of common stock were withheld by the company at $336.18 per share to satisfy tax obligations from vesting restricted stock units. After this tax-withholding transaction, Shiu directly owns 39,323 shares of Penumbra common stock and indirectly holds 300 shares through a spouse’s IRA.

Insights

Equity compensation analyst

Routine tax withholding on RSU vesting; no open-market trading.

The filing shows 150 shares of Penumbra Inc common stock withheld at $336.18 per share to cover tax obligations on vested restricted stock units for Chief Accounting Officer Lambert Shiu. This is coded as a tax-withholding disposition, not a market sale.

Following the transaction, Shiu holds 39,323 shares directly and 300 shares indirectly via a spouse’s IRA, indicating the withheld amount is small relative to the overall position. Such tax-withholding events are standard for equity compensation and typically carry limited informational value about management’s view of the 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

OMB APPROVAL

OMB Number:			3235-0287
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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^*

Shiu Lambert

(Last) (First) (Middle)

ONE PENUMBRA PLACE

(Street)

ALAMEDA CA 94502

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Penumbra Inc [ PEN ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
03/15/2026

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	03/15/2026		F(1)		150	D	$336.18	39,323(2)	D
Common Stock								300	I	By Spouse's IRA(3)

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. Shares were withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person.

2. A portion of these shares is subject to vesting.

3. Shares are held by the Reporting Person's spouse in an IRA.

Remarks:

	/s/ Johanna Roberts, as attorney-in-fact for Lambert Shiu	03/17/2026
	** 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.

FAQ

What insider transaction did Penumbra (PEN) report for Lambert Shiu?

Penumbra reported that Chief Accounting Officer Lambert Shiu had 150 shares of common stock withheld to cover tax obligations related to vested restricted stock units. This was a tax-withholding disposition, not an open-market trade, and is common for equity compensation.

Was the Penumbra (PEN) Form 4 a stock sale by Lambert Shiu?

No, the Form 4 shows a tax-withholding disposition, not an open-market sale. 150 shares were withheld by Penumbra to satisfy tax obligations from restricted stock unit vesting, a routine administrative step rather than a discretionary stock sale.

How many Penumbra (PEN) shares were involved in Lambert Shiu’s tax withholding?

The filing shows 150 shares of Penumbra common stock withheld at $336.18 per share. These shares were retained by the company to cover Shiu’s tax liability triggered by the vesting of restricted stock units, not sold on the open market.

What are Lambert Shiu’s Penumbra (PEN) holdings after the reported transaction?

After the tax-withholding transaction, Lambert Shiu directly owns 39,323 Penumbra shares. In addition, 300 shares are held indirectly through the reporting person’s spouse’s IRA, according to the Form 4 and its accompanying footnote disclosure.

Why were Penumbra (PEN) shares withheld from Lambert Shiu on March 15, 2026?

Shares were withheld to satisfy tax withholding obligations linked to vesting restricted stock units granted to Lambert Shiu. Instead of paying cash taxes, 150 shares of Penumbra stock were delivered to the issuer at $336.18 per share for this purpose.

Does Lambert Shiu have indirect ownership of Penumbra (PEN) shares?

Yes. The Form 4 notes that 300 shares of Penumbra common stock are held indirectly in the reporting person’s spouse’s IRA. This is in addition to Lambert Shiu’s 39,323 shares of direct ownership following the tax-withholding event.