Amprius CTO sells 29,681 shares for tax withholding

Amprius Technologies, Inc. (AMPX) reported that Chief Technology Officer Stefan Constantin Ionel sold 29,681 shares of common stock on 2026-08-21 at an average price of $10.341 per share.

Rhea-AI Filing Summary

Amprius Technologies, Inc. (AMPX) reported that Chief Technology Officer Stefan Constantin Ionel sold 29,681 shares of common stock on 2026-08-21 at an average price of $10.341 per share. The sale was a non-discretionary sell-to-cover mandated by the company to fund tax withholding on vested restricted stock units. After the transaction, Ionel directly held 771,629 shares of common stock, including 525,176 restricted stock units, each RSU representing a contingent right to receive one share, subject to vesting conditions.

Insider Trade Summary

Net Seller: 29,681 shares

Net Sell 1 txn

Insider Stefan Constantin Ionel

Role Chief Technology Officer

Sold 29,681 shs ($307K)

Type	Security	Shares	Price	Value
Sale	Common stock F1, F2, F3	29,681	$10.341	$307K

Holdings After Transaction: Common stock — 771,629 shares (Direct)

Footnotes (3)

1. F1. This transaction was effected pursuant to non-discretionary, sell-to-cover arrangements mandated by the issuer to fund tax withholding obligations in connection with the vesting of restricted stock units.
2. F2. The price reported in Column 4 is an average execution price. These shares were sold in multiple transactions at prices ranging from $10.10 to $10.48, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above.
3. F3. Includes 525,176 restricted stock units, each of which represents a contingent right to receive one share of the issuer's common stock, subject to the applicable vesting schedule and conditions of each restricted stock unit.

Key Figures

Shares sold: 29,681 shares Average sale price: $10.341 per share Sale price range: $10.10–$10.48 per share +2 more

5 metrics

Shares sold 29,681 shares Common stock sale on 2026-08-21 by CTO Stefan Constantin Ionel

Average sale price $10.341 per share Weighted average execution price for 29,681 shares sold

Sale price range $10.10–$10.48 per share Multiple transactions executed within this range

Shares held after transaction 771,629 shares Direct holdings of common stock by Stefan Constantin Ionel after sale

Restricted stock units included 525,176 RSUs RSUs included in post-transaction holdings, each RSU equals one share upon vesting

Key Terms

sell-to-cover, restricted stock units, average execution price

3 terms

sell-to-cover financial

"non-discretionary, sell-to-cover arrangements mandated by the issuer"

Sell-to-cover is when part of newly issued or exercised company stock is immediately sold to pay required taxes and fees, so the recipient keeps the remaining shares. For investors this matters because it reduces the number of shares insiders or employees actually hold after a grant, can create small, routine share sales that aren’t signal of cashing out, and slightly increases share supply on the market—like selling a portion of a paycheck to cover the tax bill.

restricted stock units financial

"Includes 525,176 restricted stock units, each of which represents"

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.

average execution price financial

"The price reported in Column 4 is an average execution price."

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did AMPX insider Stefan Constantin Ionel report in this Form 4?

He reported a sale of 29,681 shares of Amprius Technologies, Inc. common stock on 2026-08-21 at an average price of $10.341 per share, executed as a mandated sell-to-cover for tax withholding on vested restricted stock units.

Was the AMPX insider sale by Stefan Constantin Ionel discretionary?

No. The filing states the sale was effected pursuant to non-discretionary, sell-to-cover arrangements mandated by the issuer to fund tax withholding obligations in connection with the vesting of restricted stock units.

How many AMPX shares does Stefan Constantin Ionel hold after this transaction?

After the transaction, Stefan Constantin Ionel directly holds 771,629 shares of Amprius Technologies, Inc. common stock, which includes 525,176 restricted stock units subject to applicable vesting schedules and conditions.

What price range were the AMPX shares sold at in this Form 4?

The reported average price of $10.341 per share reflects multiple trades executed at prices ranging from $10.10 to $10.48 per share. The reporting person undertakes to provide full breakdown details upon request to interested parties.

What are the restricted stock units (RSUs) reported in this AMPX Form 4?

The filing notes that Ionel’s holdings include 525,176 restricted stock units, each representing a contingent right to receive one share of Amprius Technologies, Inc. common stock, subject to vesting schedules and conditions for each RSU grant.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 08/25/2026 - 05:22 PM EDT Accepted by SEC EDGAR 08/25/2026 - 05:22 PM EDT 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^*

Stefan Constantin Ionel

(Last) (First) (Middle)

C/O AMPRIUS TECHNOLOGIES, INC.,

1180 PAGE AVENUE

(Street)

FREMONT CALIFORNIA 94538

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Amprius Technologies, Inc. [ AMPX ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/21/2026

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	08/21/2026		S(1)		29,681	D	$10.341(2)	771,629(3)	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 was effected pursuant to non-discretionary, sell-to-cover arrangements mandated by the issuer to fund tax withholding obligations in connection with the vesting of restricted stock units.

2. The price reported in Column 4 is an average execution price. These shares were sold in multiple transactions at prices ranging from $10.10 to $10.48, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above.

3. Includes 525,176 restricted stock units, each of which represents a contingent right to receive one share of the issuer's common stock, subject to the applicable vesting schedule and conditions of each restricted stock unit.

Remarks:

	/s/ Ricardo C. Rodriguez, attorney-in-fact on behalf of Constantin Ionel Stefan	08/25/2026
	** 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)