Amprius Technologies Inc. Insider Trading

AMPX

Last 12 months

Insiders sold $85.7M and bought nothing on the open market.

75% of the selling was scheduled in advance under 10b5-1 plans. Director Wen Hsuan Hsieh sold $7.62M on Mar 12, 90% of their stake, outside a plan. No executive or director has bought shares on the open market in the last two years.

Net open-market

−$85.7M

0 buys · 27 sales

Under a 10b5-1 plan

75%

of the value sold

Insiders who bought / sold

0 / 6

executives and directors

Last open-market buy

None

in the last two years

Get an email when AMPX's executives or directors buy, or make a large sale outside a plan.

Trades · last 2 years

Date	Insider	Trade	Shares	Price	Value	Of their stake	Filing
Aug 21 – 24	Thomas M Stepien Chief Executive Officer	SoldNo plan 2 parts	31,529	$10.26 average	324K	4.9%	Form 4
Aug 21	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	29,681	$10.34	307K	3.7%	Form 4
Aug 21	Kang Sun Director	SoldNo plan	62,101	$10.34	642K	4.6%	Form 4
Jun 15	Donald R Dixon Director	SoldNo plan	85,000	$17.17	$1.46M	9.6%	Form 4
Jun 9	Donald R Dixon Director	SoldNo plan	40,000	$19.13	765K	5.3%	Form 4
Jun 4	Thomas M Stepien Chief Executive Officer	SoldNo plan	2,000	$20.97	42K	0.3%	Form 4
May 27	Thomas M Stepien Chief Executive Officer	SoldNo plan	4,375	$17.19	75K	0.6%	Form 4
May 27	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	3,208	$17.19	55K	0.4%	Form 4
May 27	Kang Sun Director	SoldNo plan	356	$17.19	6K	<0.1%	Form 4
May 26	Donald R Dixon Director	SoldNo plan	17,895	$17.90	320K	2.3%	Form 4
May 21	Thomas M Stepien Chief Executive Officer	SoldNo plan	60,702	$14.79	898K	8.0%	Form 4
May 21	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	28,812	$14.79	426K	3.5%	Form 4
May 21	Kang Sun Director	SoldNo plan	67,796	$14.79	$1M	4.8%	Form 4
Apr 1	Kang Sun Director	Sold10b5-1 plan 2 parts	1,500,000	$15.90 average	$23.9M	52%	Form 4
Mar 23	Kang Sun Director	Sold10b5-1 plan 2 parts	217,869	$18.80 average	$4.1M	13%	Form 4
Mar 12	Wen Hsuan Hsieh Director	SoldNo plan 2 parts	413,146	$18.45 average	$7.62M	90%	Form 4
Mar 10 – 12	Steven Chu Director	SoldNo plan 4 parts	322,197	$18.20 average	$5.86M	72%	Form 4
Feb 23	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	25,366	$10.16	258K	3.4%	Form 4
Feb 23	Kang Sun Director	SoldNo plan	61,251	$10.16	622K	3.7%	Form 4
Jan 28	Constantin Ionel Stefan Chief Technology Officer	Sold10b5-1 plan	39,690	$12.00	476K	5.0%	Form 4
Jan 21 – 23	Constantin Ionel Stefan Chief Technology Officer	Sold10b5-1 plan 3 parts	567,707	$12.03 average	$6.83M	43%	Form 4
Jan 16 – 20	Kang Sun Director	Sold10b5-1 plan 2 parts	993,733	$11.07 average	$11M	37%	Form 4
Jan 12	Kang Sun Director	Sold10b5-1 plan	506,267	$10.10	$5.11M	23%	Form 4
Dec 11, 2025	Constantin Ionel Stefan Chief Technology Officer	Sold10b5-1 plan	198,255	$10.51	$2.08M	21%	Form 4
Nov 21, 2025	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	25,024	$10.08	252K	3.0%	Form 4
Nov 21, 2025	Kang Sun Chief Executive Officer	SoldNo plan	68,655	$10.08	692K	3.9%	Form 4
Nov 17, 2025	Kang Sun Chief Executive Officer	Sold10b5-1 plan	1,000,000	$10.60	$10.6M	36%	Form 4
Aug 21, 2025	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	19,159	$6.82	131K	2.2%	Form 4
Aug 21, 2025	Sandra Wallach Chief Financial Officer	SoldNo plan	28,390	$6.82	194K	2.7%	Form 4
Aug 21, 2025	Kang Sun Chief Executive Officer	SoldNo plan	65,654	$6.82	448K	3.6%	Form 4
May 21, 2025	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	20,366	$2.43	49K	2.3%	Form 4
May 21, 2025	Sandra Wallach Chief Financial Officer	SoldNo plan	27,595	$2.43	67K	2.6%	Form 4
May 21, 2025	Kang Sun Chief Executive Officer	SoldNo plan	69,786	$2.43	170K	3.7%	Form 4
Feb 21, 2025	Jonathan Bornstein President of Amprius Lab	SoldNo plan	13,527	$3.13	42K	0.9%	Form 4
Feb 21, 2025	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	9,066	$3.13	28K	2.1%	Form 4
Feb 21, 2025	Sandra Wallach Chief Financial Officer	SoldNo plan	18,142	$3.13	57K	2.6%	Form 4
Feb 21, 2025	Kang Sun Chief Executive Officer	SoldNo plan	34,353	$3.13	108K	2.6%	Form 4
Nov 20, 2024 – Nov 21, 2024	Jonathan Bornstein President of Amprius Lab	SoldNo plan 3 parts	166,706	$1.93 average	321K	10%	Form 4
Nov 21, 2024	Constantin Ionel Stefan Chief Technology Officer	SoldNo plan	8,575	$1.96	17K	2.0%	Form 4
Nov 21, 2024	Sandra Wallach Chief Financial Officer	SoldNo plan	17,158	$1.96	34K	2.4%	Form 4

Aug 21 – 24No plan
Thomas M Stepien
Chief Executive Officer · sold 31,529 at avg $10.26
324K
4.9% of stake
Aug 21No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 29,681 at $10.34
307K
3.7% of stake
Aug 21No plan
Kang Sun
Director · sold 62,101 at $10.34
642K
4.6% of stake
Jun 15No plan
Donald R Dixon
Director · sold 85,000 at $17.17
$1.46M
9.6% of stake
Jun 9No plan
Donald R Dixon
Director · sold 40,000 at $19.13
765K
5.3% of stake
Jun 4No plan
Thomas M Stepien
Chief Executive Officer · sold 2,000 at $20.97
42K
0.3% of stake
May 27No plan
Thomas M Stepien
Chief Executive Officer · sold 4,375 at $17.19
75K
0.6% of stake
May 27No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 3,208 at $17.19
55K
0.4% of stake
May 27No plan
Kang Sun
Director · sold 356 at $17.19
6K
<0.1% of stake
May 26No plan
Donald R Dixon
Director · sold 17,895 at $17.90
320K
2.3% of stake
May 21No plan
Thomas M Stepien
Chief Executive Officer · sold 60,702 at $14.79
898K
8.0% of stake
May 21No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 28,812 at $14.79
426K
3.5% of stake
May 21No plan
Kang Sun
Director · sold 67,796 at $14.79
$1M
4.8% of stake
Apr 110b5-1 plan
Kang Sun
Director · sold 1,500,000 at avg $15.90
$23.9M
52% of stake
Mar 2310b5-1 plan
Kang Sun
Director · sold 217,869 at avg $18.80
$4.1M
13% of stake
Mar 12No plan
Wen Hsuan Hsieh
Director · sold 413,146 at avg $18.45
$7.62M
90% of stake
Mar 10 – 12No plan
Steven Chu
Director · sold 322,197 at avg $18.20
$5.86M
72% of stake
Feb 23No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 25,366 at $10.16
258K
3.4% of stake
Feb 23No plan
Kang Sun
Director · sold 61,251 at $10.16
622K
3.7% of stake
Jan 2810b5-1 plan
Constantin Ionel Stefan
Chief Technology Officer · sold 39,690 at $12.00
476K
5.0% of stake
Jan 21 – 2310b5-1 plan
Constantin Ionel Stefan
Chief Technology Officer · sold 567,707 at avg $12.03
$6.83M
43% of stake
Jan 16 – 2010b5-1 plan
Kang Sun
Director · sold 993,733 at avg $11.07
$11M
37% of stake
Jan 1210b5-1 plan
Kang Sun
Director · sold 506,267 at $10.10
$5.11M
23% of stake
Dec 11, 202510b5-1 plan
Constantin Ionel Stefan
Chief Technology Officer · sold 198,255 at $10.51
$2.08M
21% of stake
Nov 21, 2025No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 25,024 at $10.08
252K
3.0% of stake
Nov 21, 2025No plan
Kang Sun
Chief Executive Officer · sold 68,655 at $10.08
692K
3.9% of stake
Nov 17, 202510b5-1 plan
Kang Sun
Chief Executive Officer · sold 1,000,000 at $10.60
$10.6M
36% of stake
Aug 21, 2025No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 19,159 at $6.82
131K
2.2% of stake
Aug 21, 2025No plan
Sandra Wallach
Chief Financial Officer · sold 28,390 at $6.82
194K
2.7% of stake
Aug 21, 2025No plan
Kang Sun
Chief Executive Officer · sold 65,654 at $6.82
448K
3.6% of stake
May 21, 2025No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 20,366 at $2.43
49K
2.3% of stake
May 21, 2025No plan
Sandra Wallach
Chief Financial Officer · sold 27,595 at $2.43
67K
2.6% of stake
May 21, 2025No plan
Kang Sun
Chief Executive Officer · sold 69,786 at $2.43
170K
3.7% of stake
Feb 21, 2025No plan
Jonathan Bornstein
President of Amprius Lab · sold 13,527 at $3.13
42K
0.9% of stake
Feb 21, 2025No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 9,066 at $3.13
28K
2.1% of stake
Feb 21, 2025No plan
Sandra Wallach
Chief Financial Officer · sold 18,142 at $3.13
57K
2.6% of stake
Feb 21, 2025No plan
Kang Sun
Chief Executive Officer · sold 34,353 at $3.13
108K
2.6% of stake
Nov 20, 2024 – Nov 21, 2024No plan
Jonathan Bornstein
President of Amprius Lab · sold 166,706 at avg $1.93
321K
10% of stake
Nov 21, 2024No plan
Constantin Ionel Stefan
Chief Technology Officer · sold 8,575 at $1.96
17K
2.0% of stake
Nov 21, 2024No plan
Sandra Wallach
Chief Financial Officer · sold 17,158 at $1.96
34K
2.4% of stake

How to read this. Insiders sell for many reasons: taxes, diversifying, a house. Open-market buys are rarer and say more. A 10b5-1 plan is a trading schedule set up months in advance, so those sales were not timed on news. Large holders (funds and 10% owners) are listed under Everything but not counted as insiders. If you own or watch AMPX, we send a push when an executive buys or makes a large sale outside a plan.

Source: SEC Form 4 filings, filed within two business days of each trade and checked for new ones every hour.

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Held by ETFs

AMPX is in 44 US ETFs. The largest of them, with AMPX's weight in each:

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Data sourced from SEC EDGAR filings and third-party price providers. Scores, valuations, and metrics are algorithmic estimates. This is not investment advice. See our Terms and Methodology.

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