ACM Research, Inc.
US ˙ NasdaqGM ˙ US00108J1097

SecurityACMR / ACM Research, Inc.
InstitutionCitigroup Inc
Latest Disclosed Ownership619,892 shares
Latest Disclosed Value $ 24,392,750
Citigroup Inc ownership in ACMR / ACM Research, Inc.

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 619,892 shares of ACM Research, Inc. (US:ACMR) valued at $24,392,750 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 43,752 shares of ACM Research, Inc.. This represents a change in shares of 1,316.83% during the quarter. The current value of the position is $55,083,603 USD.

Citigroup Inc has a history of taking positions in derivatives of the underlying security (ACMR) in the form of stock options. The firm currently holds call options representing 486,000 of underlying shares valued at $19,124,100 USD and put options representing 486,000 of underlying shares valued at $19,124,100 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

Upgrade to unlock premium data and export to Excel .

Institutional Put/Call Ratios
(Premium Subscription Required)

In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

ACMR / ACM Research, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-11 2026-03-31 13F ACM RESH COM CL A 00108J109 619,892 576,140 1,316.83 24,393 1,313.21 0.0104
2026-02-13 2025-12-31 13F ACM RESH COM CL A 00108J109 43,752 19,522 80.57 1,726 82.07 0.0008
2025-11-10 2025-09-30 13F ACM RESH COM CL A 00108J109 24,230 -213,787 -89.82 948 -84.62 0.0004
2025-08-11 2025-06-30 13F ACM RESH COM CL A 00108J109 238,017 -104,802 -30.57 6,165 -22.96 0.0030
2025-05-12 2025-03-31 13F ACM RESH COM CL A 00108J109 342,819 -897 -0.26 8,001 54.16 0.0041
2025-02-12 2024-12-31 13F ACM RESH COM CL A 00108J109 343,716 3,509 1.03 5,190 -24.85 0.0031
2024-11-12 2024-09-30 13F ACM RESH COM CL A 00108J109 340,207 27,178 8.68 6,906 -4.32 0.0040
2024-08-12 2024-06-30 13F ACM RESH COM CL A 00108J109 313,029 -281,244 -47.33 7,218 -58.32 0.0046
2024-05-10 2024-03-31 13F ACM RESH COM CL A 00108J109 594,273 -1,142,323 -65.78 17,317 -48.97 0.0114
2024-02-09 2023-12-31 13F ACM RESH COM CL A 00108J109 1,736,596 -29,027 -1.64 33,933 6.15 0.0239
2023-12-06 2023-09-30 13F/A-1 ACM RESH COM CL A 00108J109 1,765,623 -13,009 -0.73 31,967 37.41 0.0239
2023-11-09 2023-09-30 13F ACM RESH COM CL A 00108J109 1,765,623 -13,009 31,967 0.0096
2023-08-10 2023-06-30 13F ACM RESH COM CL A 00108J109 1,778,632 15,983 0.91 23,265 12.81 0.0153
2023-05-11 2023-03-31 13F ACM RESH COM CL A 00108J109 1,762,649 -480 -0.03 20,623 51.71 0.0145
2023-02-09 2022-12-31 13F ACM RESH COM CL A 00108J109 1,763,129 7 0.00 13,594 -38.13 0.0108
2022-11-10 2022-09-30 13F ACM RESH COM CL A 00108J109 1,763,122 1,153,063 189.01 21,969 113.98 0.0157
2022-08-10 2022-06-30 13F ACM RESH COM CL A 00108J109 610,059 602,856 8,369.51 10,267 6,790.60 0.0076
2022-05-12 2022-03-31 13F ACM RESH COM CL A 00108J109 7,203 2,963 69.88 149 -58.73 0.0001
2022-02-10 2021-12-31 13F ACM RESH COM CL A 00108J109 4,240 2,360 125.53 361 74.40 0.0002
2021-11-10 2021-09-30 13F ACM RESH COM CL A 00108J109 1,880 1,547 464.56 207 508.82 0.0001
2021-08-10 2021-06-30 13F ACM RESH COM CL A 00108J109 333 111 50.00 34 88.89 0.0000
2021-05-13 2021-03-31 13F ACM RESEARCH COM CL A 00108J109 222 -15 -6.33 18 -5.26 0.0000
2021-02-11 2020-12-31 13F ACM RESEARCH COM CL A 00108J109 237 119 100.85 19 137.50 0.0000
2020-11-12 2020-09-30 13F ACM RESEARCH COM CL A 00108J109 118 -16,297 -99.28 8 -99.22 0.0000
2020-08-12 2020-06-30 13F ACM RESEARCH COM CL A 00108J109 16,415 16,415 1,024 0.0008
2020-02-12 2019-12-31 13F ACM RESEARCH COM CL A 00108J109 0 -943 -100.00 0 -100.00
2019-11-08 2019-09-30 13F ACM RESEARCH COM CL A 00108J109 943 -5,136 -84.49 13 -86.32 0.0000
2019-08-12 2019-06-30 13F ACM RESEARCH COM CL A 00108J109 6,079 3,800 166.74 95 171.43 0.0001
2019-05-13 2019-03-31 13F ACM RESEARCH COM CL A 00108J109 2,279 432 23.39 35 75.00 0.0000
2019-02-12 2018-12-31 13F ACM RESEARCH COM CL A 00108J109 1,847 -451 -19.63 20 -20.00 0.0000
2018-11-13 2018-09-30 13F ACM RESEARCH COM CL A 00108J109 2,298 1,131 96.92 25 92.31 0.0000
2018-08-10 2018-06-30 13F ACM RESEARCH COM CL A 00108J109 1,167 1,167 13 0.0000
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-11 2026-03-31 13F ACM RESH COM CL A Call 486,000 19,124 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-11 2026-03-31 13F ACM RESH COM CL A Put 486,000 19,124 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.