Constantin Ionel Stefan - 27 May 2026 Form 4 Insider Report for Amprius Technologies, Inc. (AMPX)

Reporting relationship: Chief Technology Officer
Issuer ticker: AMPX
Reported as of: 27 May 2026
Net transaction value: -$55,157
SEC form: 4
Accepted by SEC: 28 May 2026, 18:12:28 UTC
Prior SEC filing: 26 May 2026
Source filing: View source filing
Reporting owner signature: /s/ Ricardo C. Rodriguez, attorney-in-fact on behalf of Constantin Ionel Stefan

Key filing fact

Constantin Ionel Stefan filed Form 4 for Amprius Technologies, Inc. (AMPX) on 28 May 2026.

Key facts

This page summarizes Constantin Ionel Stefan's Form 4 filing for Amprius Technologies, Inc. (AMPX).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 28 May 2026, 18:12.

Change

Previous filing in this sequence was filed on 26 May 2026.
Current net transaction value: -$55,157.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001940928 Primary reporting owner

Stefan Constantin Ionel

Relationship: Chief Technology Officer
Address: C/O AMPRIUS TECHNOLOGIES, INC.,, 1180 PAGE AVENUE, FREMONT
Signature: /s/ Ricardo C. Rodriguez, attorney-in-fact on behalf of Constantin Ionel Stefan
Signature date: 28 May 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

AMPX transaction

Common stock

Sale

Transaction value: $55,157
Shares: -3,208
Change %: -0.4%
Price: $17.19
Shares after: 801,310
Date: 27 May 2026
Ownership: Direct
Footnotes: F1, F2, F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 3 footnotes

Footnote 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.

Footnote F2

The price reported in Column 4 is an average execution price. These shares were sold in multiple transactions at prices ranging from $17.13 to $17.3, 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.

Footnote F3

Includes 584,308 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.