CHEAV SOTHEARA (See remarks) sold 15.8% of their position (18.75K shares) of ACM RESEARCH, INC. on the open market

Open‑market sale worth $1.59M — a significant reduction. Review remaining holdings and any 10b5‑1 plan disclosures.

S · 7 sales

CHEAV SOTHEARA

Filed: 6/6/2026ACC: 0001140361-26-024322

InsiderCHEAV SOTHEARACIK 1721279

→

IssuerACM RESEARCH, INC.CIK 1680062

Officer· See remarks

Since Jun 2018

-18.75K

Net shares

Net seller

$1.59M

Total sold

Open market trades

0B · 7S

Total transactions

18.75K acquired · 37.50K disposed

Non-Derivative Transactions9

Class A Common Stock

Direct

M · Option Exercise

+13.35K

Price / share

$13.89

Trade value

$185.45K

% of position

13.4%

6/4/2026

100K→113.35K

Class A Common Stock

Direct

S · Sale

−1.30K

Price / share

$84.08

Trade value

$109.30K

% of position

1.1%

6/4/2026

113.35K→112.05K

Class A Common Stock

Direct

S · Sale

−9.21K

Price / share

$85.11

Trade value

$784.03K

% of position

8.2%

6/4/2026

112.05K→102.84K

Class A Common Stock

Direct

S · Sale

−2.84K

Price / share

$85.77

Trade value

$243.50K

% of position

2.8%

6/4/2026

102.84K→100K

Class A Common Stock

Direct

M · Option Exercise

+5.40K

Price / share

$13.89

Trade value

$74.99K

% of position

5.4%

6/5/2026

100K→105.40K

Class A Common Stock

Direct

S · Sale

−2.38K

Price / share

$81.73

Trade value

$194.84K

% of position

2.3%

6/5/2026

105.40K→103.02K

Class A Common Stock

Direct

S · Sale

−968.00

Price / share

$82.61

Trade value

$79.97K

% of position

0.9%

6/5/2026

103.02K→102.05K

Class A Common Stock

Direct

S · Sale

−400.00

Price / share

$84.01

Trade value

$33.60K

% of position

0.4%

6/5/2026

102.05K→101.65K

Class A Common Stock

Direct

S · Sale

−1.65K

Price / share

$85.41

Trade value

$140.67K

% of position

1.6%

6/5/2026

101.65K→100K

Total

Net shares

+0.00

Net value

-$1.33M

Security	Date	Type	Shares	Price / Share	Trade Value	% of Position	Held Before	Held After
Class A Common Stock Direct	6/4/2026	M · Option Exercise	+13.35K	$13.89	$185.45K	13.4%	100K	113.35K
Class A Common Stock Direct	6/4/2026	S · Sale	−1.30K	$84.08	$109.30K	1.1%	113.35K	112.05K
Class A Common Stock Direct	6/4/2026	S · Sale	−9.21K	$85.11	$784.03K	8.2%	112.05K	102.84K
Class A Common Stock Direct	6/4/2026	S · Sale	−2.84K	$85.77	$243.50K	2.8%	102.84K	100K
Class A Common Stock Direct	6/5/2026	M · Option Exercise	+5.40K	$13.89	$74.99K	5.4%	100K	105.40K
Class A Common Stock Direct	6/5/2026	S · Sale	−2.38K	$81.73	$194.84K	2.3%	105.40K	103.02K
Class A Common Stock Direct	6/5/2026	S · Sale	−968.00	$82.61	$79.97K	0.9%	103.02K	102.05K
Class A Common Stock Direct	6/5/2026	S · Sale	−400.00	$84.01	$33.60K	0.4%	102.05K	101.65K
Class A Common Stock Direct	6/5/2026	S · Sale	−1.65K	$85.41	$140.67K	1.6%	101.65K	100K
Total			+0.00		-$1.33M

Derivative Transactions2

Stock Option

Direct

M · Option Exercise

Converts to

Class A Common Stock

13.35K shares

−13.35K

Strike price

13.89

Held after

42.90K

Exercisable

—

6/4/2026

Stock Option

Direct

M · Option Exercise

Converts to

Class A Common Stock

5.40K shares

−5.40K

Strike price

13.89

Held after

37.50K

Exercisable

—

6/5/2026

Security	Converts To	Date	Type	Shares	Strike Price	Exercisable	Held After
Stock Option Direct	Class A Common Stock13.35K shares	6/4/2026	M · Option Exercise	−13.35K	13.89	—	42.90K
Stock Option Direct	Class A Common Stock5.40K shares	6/5/2026	M · Option Exercise	−5.40K	13.89	—	37.50K