Amprius CTO sells 28,812 shares in tax sale

Amprius Technologies, Inc. Chief Technology Officer Stefan Constantin Ionel reported an open-market sale of 28,812 shares of common stock on May 21, 2026 at an average price of $14.7884 per share.

Rhea-AI Filing Summary

Amprius Technologies, Inc. Chief Technology Officer Stefan Constantin Ionel reported an open-market sale of 28,812 shares of common stock on May 21, 2026 at an average price of $14.7884 per share. According to the disclosure, this sale was a non-discretionary, sell-to-cover transaction mandated by the company to fund tax withholding obligations related to vesting restricted stock units. After the sale, Ionel directly held 804,518 shares of common stock, including 591,183 restricted stock units that may convert into shares as vesting conditions are met.

Insider Trade Summary

Net Seller: 28,812 shares

Net Sell 1 txn

Insider Stefan Constantin Ionel

Role Chief Technology Officer

Sold 28,812 shs ($426K)

Type	Security	Shares	Price	Value
Sale	Common stock	28,812	$14.7884	$426K

Holdings After Transaction: Common stock — 804,518 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 $14.54 to $15.08, 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 591,183 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: 28,812 shares Average sale price: $14.7884 per share Sale price range: $14.54–$15.08 per share +2 more

5 metrics

Shares sold 28,812 shares Open-market sale on May 21, 2026

Average sale price $14.7884 per share Consideration for 28,812 shares sold

Sale price range $14.54–$15.08 per share Multiple transactions within this range

Shares held after transaction 804,518 shares Direct common stock holdings post-sale

Restricted stock units held 591,183 RSUs RSUs that may settle into common shares upon vesting

Key Terms

restricted stock units, sell-to-cover arrangements, tax withholding obligations, average execution price

4 terms

restricted stock units financial

"Includes 591,183 restricted stock units, each of which represents a contingent right to receive one share"

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.

sell-to-cover arrangements financial

"transaction was effected pursuant to non-discretionary, sell-to-cover arrangements mandated by the issuer"

tax withholding obligations financial

"arrangements mandated by the issuer to fund tax withholding obligations in connection with the vesting"

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 insider transaction did Amprius Technologies (AMPX) report for its CTO?

Amprius Technologies reported that CTO Stefan Constantin Ionel sold 28,812 common shares at an average price of $14.7884 on May 21, 2026. The transaction was an open-market sale tied to tax withholding obligations from vesting restricted stock units.

Why did the Amprius (AMPX) CTO sell 28,812 shares of stock?

The CTO’s 28,812-share sale was executed under non-discretionary, sell-to-cover arrangements mandated by Amprius. The proceeds were used to fund tax withholding obligations triggered by the vesting of restricted stock units granted as part of his compensation.

How many Amprius (AMPX) shares does the CTO hold after this Form 4 sale?

Following the reported sale, CTO Stefan Constantin Ionel holds 804,518 shares of Amprius common stock directly. This total includes 591,183 restricted stock units that represent contingent rights to receive shares as vesting schedules and conditions are satisfied over time.

What price range applied to the Amprius (AMPX) CTO’s share sale?

The average reported price for the 28,812 shares sold was $14.7884, with individual trades executed between $14.54 and $15.08 per share. The CTO undertook to provide full breakdowns of shares sold at each price upon request to interested parties.

Was the Amprius (AMPX) CTO’s stock sale discretionary or pre-arranged?

The sale was described as non-discretionary, occurring under mandated sell-to-cover arrangements. These arrangements were required by Amprius to generate cash for tax withholding obligations associated with the vesting of the CTO’s restricted stock units, rather than a voluntary portfolio decision.

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

The filing notes 591,183 restricted stock units held by the CTO, each representing a contingent right to one Amprius common share. These units convert into shares only if the specified vesting schedules and other applicable conditions set by the company are met.

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

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Accepted by SEC EDGAR 05/26/2026 - 07:10 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^*

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)
05/21/2026

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	05/21/2026		S(1)		28,812	D	$14.7884(2)	804,518(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 $14.54 to $15.08, 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 591,183 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	05/26/2026
	** 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)