Constantin Ionel Stefan - 28 Jan 2026 Form 4 Insider Report for Amprius Technologies, Inc. (AMPX)

Reporting relationship: Chief Technology Officer
Issuer ticker: AMPX
Reported as of: 28 Jan 2026
Net transaction value: -$474,316
SEC form: 4
Accepted by SEC: 30 Jan 2026, 18:02:40 UTC
Prior SEC filing: 23 Jan 2026
Next SEC filing: 24 Feb 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 30 Jan 2026.

Key facts

This page summarizes Constantin Ionel Stefan's Form 4 filing for Amprius Technologies, Inc. (AMPX).
5 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 30 Jan 2026, 18:02.

Change

Previous filing in this sequence was filed on 23 Jan 2026.
Current net transaction value: -$474,316.

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: 30 Jan 2026

Reported non-derivative transactions

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

AMPX transaction

Common stock

Options Exercise

Transaction value: $55.8
Shares: +90
Change %: +0.01%
Price: $0.6200
Shares after: 748,786
Date: 28 Jan 2026
Ownership: Direct
Footnotes: F1, F2

AMPX transaction

Common stock

Options Exercise

Transaction value: $1,980
Shares: +39,600
Change %: +5.3%
Price: $0.0500
Shares after: 788,386
Date: 28 Jan 2026
Ownership: Direct
Footnotes: F1, F2

AMPX transaction

Common stock

Sale

Transaction value: $476,351
Shares: -39,690
Change %: -5%
Price: $12.00
Shares after: 748,696
Date: 28 Jan 2026
Ownership: Direct
Footnotes: F1, F2, F3

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

AMPX transaction Derivative

Stock Option (right to buy)

Options Exercise

Transaction value: $0
Shares: -90
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 28 Jan 2026
Ownership: Direct
Underlying class: Common stock
Underlying amount: 90
Exercise price: $0.6200
Footnotes: F1

AMPX transaction Derivative

Stock Option (right to buy)

Options Exercise

Transaction value: $0
Shares: -39,600
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 28 Jan 2026
Ownership: Direct
Underlying class: Common stock
Underlying amount: 39,600
Exercise price: $0.0500
Footnotes: F1

^* 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

The exercises and sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 11, 2025.

Footnote F2

Includes 585,697 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.

Footnote F3

The price reported in Column 4 is an average execution price. These shares were sold in multiple transactions at prices ranging from $12.00 to $12.02, 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.