Amprius Technologies (NASDAQ: AMPX) insider plans up to 29,681-share sale for taxes

Rhea-AI Filing Summary

Amprius Technologies, Inc. (symbol AMPX) has an affiliate, officer Constantin Ionel Stefan, filing a notice of proposed sale of restricted securities under Rule 144. The notice contemplates the potential sale of up to 29,681 shares of Amprius common stock through Morgan Stanley Smith Barney LLC, with an aggregate market value of $306,930.27 as of the filing details. These shares relate to the 08/20/2026 release of 59,132 restricted stock units received from the issuer as compensation, and the filer states the shares are to be sold to cover withholding taxes upon vesting. Over the prior three months, the filer reported a sale of 3,208 shares of common stock on 05/27/2026 for $55,156.75.

Key Figures

Proposed shares to be sold: 29,681 shares Aggregate market value of proposed sale: $306,930.27 Restricted stock units released: 59,132 units +4 more

7 metrics

Proposed shares to be sold 29,681 shares Common stock to be sold through Morgan Stanley Smith Barney LLC under Rule 144

Aggregate market value of proposed sale $306,930.27 Aggregate market value associated with 29,681 proposed shares of common stock

Restricted stock units released 59,132 units Restricted stock units released on 08/20/2026 from issuer as compensation

Prior 3-month sale shares 3,208 shares Common stock sold on 05/27/2026 during the past three months

Proceeds from prior 3-month sale $55,156.75 Total amount received for 3,208 shares sold on 05/27/2026

Date of RSU release 08/20/2026 Date of release of 59,132 restricted stock units from issuer as compensation

Date of notice 08/25/2026 Date the Rule 144 notice was signed by Constantin Ionel Stefan

Key Terms

Rule 144, restricted stock units, withholding taxes, compensation

4 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

restricted stock units financial

"Release of restricted stock units | Issuer | | | 59132"

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.

withholding taxes financial

"SHARES TO BE SOLD TO COVER WITHHOLDING TAXES UPON VESTING"

Withholding taxes are amounts a payer or government takes out of payments — such as wages, interest, or dividends — before the recipient gets the money, functioning like a cashier keeping part of a bill to pay taxes on your behalf. For investors this matters because it reduces the cash they actually receive, affects net returns and yield calculations, and may require additional paperwork or treaty claims to recover or offset the withheld amount against final tax bills.

compensation financial

"59132 | 08/20/2026 | Compensation"

FAQ

What does the Form 144 filing by an officer of AMPX disclose?

The filing discloses that officer Constantin Ionel Stefan has filed a notice of intent under Rule 144 to potentially sell up to 29,681 shares of Amprius Technologies, Inc. common stock, relating to vested restricted stock units and intended to cover withholding taxes upon vesting.

How many AMPX shares are proposed to be sold under this Form 144?

The notice contemplates the potential sale of up to 29,681 shares of Amprius Technologies, Inc. common stock, with an indicated aggregate market value of $306,930.27 tied to this proposed Rule 144 transaction.

What is the origin of the AMPX shares covered by this Form 144?

The shares arise from the release of restricted stock units. On 08/20/2026, 59,132 restricted stock units of Amprius common stock were released to the filer from the issuer as compensation, and a portion is expected to be sold to cover tax withholding.

Has the AMPX insider sold shares recently before this notice?

Yes. During the past three months, the filer reported selling 3,208 shares of Amprius common stock on 05/27/2026 for total proceeds of $55,156.75, as reflected in the historical sales section of the notice.

Which broker is listed for the proposed AMPX share sale and on which market?

The proposed sale lists Morgan Stanley Smith Barney LLC, located at 1 New York Plaza, as the broker for up to 29,681 shares of Amprius common stock, with the shares indicated for trading on the NYSE.

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

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Available on EDGAR 08/25/2026 - 05:22 PM Accepted by SEC EDGAR 08/25/2026 - 05:21 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001940928
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	AMPRIUS TECHNOLOGIES, INC
SEC File Number	001-41314
Address of Issuer	1180 Page Avenue Fremont CALIFORNIA 94538
Phone	8004258803
Name of Person for Whose Account the Securities are To Be Sold	Constantin Ionel Stefan
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	OFFICER

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC 1 New York Plaza, 38th fl. New York NY 10004	29681	306930.27	146080618	08/21/2026	NYSE

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	08/20/2026	Release of restricted stock units	Issuer			59132	08/20/2026	Compensation

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Constantin Ionel Stefan 1180 Page Avenue Fremont CA 94538	Common Stock	05/27/2026	3208	55156.75

144: Remarks and Signature

Remarks	SHARES TO BE SOLD TO COVER WITHHOLDING TAXES UPON VESTING OF RESTRICTED STOCK UNIT AWARDS
Date of Notice	08/25/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/Constantin Ionel Stefan
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)