Portolan Capital Management’s ACM Research ACMR Stock Holding History

Portolan Capital Management’s Portfolio ACMR Stock Details ACMR Fund Activity

Bought

Maintained

Sold

Quarter	Market Value	Status	Shares	Change in Stake	Trade Value	Portfolio Weight	Portfolio Position
2026 Q1	$3.28M	Sell	83,256 -202,250	-71%	-$10.7M	0.17%	116
2025 Q4	$11.3M	Sell	285,506 -120,354	-30%	-$4.48M	0.6%	58
2025 Q3	$15.9M	Buy	+405,860	New	+$12M	0.86%	37
2024 Q4	–	Sell	-921,451	Closed	-$18.7M	–	132
2024 Q3	$18.7M	Buy	921,451 +65,616	+8%	+$1.26M	1.36%	20
2024 Q2	$19.7M	Buy	855,835 +317,402	+59%	+$8.03M	1.63%	15
2024 Q1	$15.7M	Sell	538,433 -261,071	-33%	-$5.98M	1.2%	30
2023 Q4	$15.6M	Buy	+799,504	New	+$14M	1.37%	18
2023 Q2	–	Sell	-561,894	Closed	-$6.57M	–	121
2023 Q1	$6.57M	Buy	+561,894	New	+$6.5M	0.63%	56

Other funds holding ACMR

BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return

VCM

Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM

VPM

Vanguard Portfolio Management Malvern, Pennsylvania $1.91T AUM

State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return

WCM Investment Management Laguna Beach, California $43.8B AUM 42.28% 1-Year Est. Return

Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return

Morgan Stanley New York $1.66T AUM 25.57% 1-Year Est. Return

Janus Henderson Group London, United Kingdom $209B AUM 37.72% 1-Year Est. Return

VARA

Value Aligned Research Advisors Princeton, New Jersey $20.7B AUM 292.88% 1-Year Est. Return

PCP

Polunin Capital Partners London, United Kingdom $407M AUM 55.12% 1-Year Est. Return

Portolan Capital Management's ACMR Position: Q1 2026 in Review

Portolan Capital Management reduced its ACM Research (ACMR) stake by 71% in Q1 2026, selling an estimated $10.7M and leaving 83,256 shares worth $3.28M. The position accounts for 0.17% of the portfolio, ranked #116.

Portolan Capital Management first reported a position in ACMR in Q1 2023 and has held it in 8 quarters since. The position peaked at $19.7M in Q2 2024. 300 funds tracked by Wall St. Rank hold ACMR as of Q1 2026.

Portolan Capital Management held 83,256 shares of ACM Research worth $3.28M as of Q1 2026.
Portolan Capital Management sold 202,250 ACM Research shares in Q1 2026, an estimated $10.7M.
ACM Research made up 0.17% of Portolan Capital Management's portfolio in Q1 2026, its #116 holding.
Portolan Capital Management first reported a position in ACM Research in Q1 2023 and has held it in 8 quarters since.
Portolan Capital Management's ACM Research position peaked at $19.7M in Q2 2024.
300 funds tracked by Wall St. Rank held ACM Research as of Q1 2026.

Based on Portolan Capital Management's 13F filing for Q1 2026, filed 15 May 2026.