Amprius director to sell 126,974 shares for taxes

Amprius Technologies, Inc. (AMPX) received a notice that director Kang Sun intends to sell company common stock under Rule 144.

Rhea-AI Filing Summary

Amprius Technologies, Inc. (AMPX) received a notice that director Kang Sun intends to sell company common stock under Rule 144. The planned sale relates to 126,974 shares expected from the release of restricted stock units on 08/20/2026, with the stated purpose of covering withholding taxes upon vesting.

Morgan Stanley Smith Barney LLC is listed as the broker. The notice also lists a prior Rule 10b5-1 sale of 356 shares of common stock on 05/27/2026 for $6,120.89 during the past three months.

Key Figures

Planned shares to be sold: 126,974 shares of common stock RSU release date: 08/20/2026 Shares sold in past 3 months: 356 shares of common stock +3 more

6 metrics

Planned shares to be sold 126,974 shares of common stock To be sold in connection with RSU release on 08/20/2026

RSU release date 08/20/2026 Date tied to restricted stock unit vesting and planned sale

Shares sold in past 3 months 356 shares of common stock Rule 10b5-1 sale on 05/27/2026

Proceeds from recent sale $6,120.89 Total for 356 shares sold on 05/27/2026

Issuer file number 001-41314 SEC file number for Amprius Technologies, Inc.

Date of notice 08/25/2026 Date the Rule 144 notice was signed by Kang Sun

Key Terms

Rule 144, restricted stock units, withholding taxes, 10b5-1

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 | | | 126974"

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.

10b5-1 regulatory

"10b5-1 Sales for KANG SUN 1180 Page Ave."

A 10b5-1 plan is a pre-set schedule that lets company insiders buy or sell shares according to written instructions made when they do not possess material, nonpublic information. Think of it as a timed automatic payment for stock trades: it helps insiders avoid accusations of trading on secret information and gives outside investors a clearer signal about whether sales are routine or potentially informative about the company’s prospects.

FAQ

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

What insider transaction did AMPX disclose in this Form 144 filing?

The filing states that director Kang Sun intends to sell 126,974 shares of Amprius Technologies common stock in connection with the 08/20/2026 release of restricted stock units, primarily to cover withholding taxes upon vesting.

How many AMPX shares are planned to be sold to cover tax withholding?

The notice reports that 126,974 common shares of Amprius Technologies are expected to be sold in connection with the vesting of restricted stock unit awards, with the remark that the shares are to be sold to cover withholding taxes.

Which broker is handling the planned AMPX share sale for Kang Sun?

The filing lists Morgan Stanley Smith Barney LLC, located at 1 New York Plaza, New York, as the broker for the Amprius Technologies common stock associated with this Rule 144 notice.

Were there any AMPX shares sold by Kang Sun in the past three months?

Yes. The filing reports a Rule 10b5-1 sale of 356 Amprius Technologies common shares on 05/27/2026 for total proceeds of $6,120.89 during the past three months.

What is the stated reason for Kang Sun’s planned AMPX share sale?

The remarks section explains that the shares are to be sold to cover withholding taxes upon the vesting of restricted stock unit awards, linking the transaction to compensation-related tax obligations rather than a discretionary open-market sale.

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

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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

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	0001476220
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	KANG SUN
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	Director

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	62101	642184.45	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			126974	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
10b5-1 Sales for KANG SUN 1180 Page Ave. Fremont CA 94538	Common	05/27/2026	356	6120.89

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/ Kang Sun
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)