Monolithic Power Systems, Inc.
MX ˙ BMV ˙ US6098391054
SecurityMX:MPWR / Monolithic Power Systems, Inc.
InstitutionOppenheimer & Co Inc
Latest Disclosed Ownership6,667 shares
Latest Disclosed Value $ 7,289,364
Oppenheimer & Co Inc reports 2.51% decrease in ownership of MPWR / Monolithic Power Systems, Inc.

On April 23, 2026 - Oppenheimer & Co Inc filed a 13F-HR form disclosing ownership of 6,667 shares of Monolithic Power Systems, Inc. (MX:MPWR) valued at $7,289,364 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 2, 2026 disclosing 6,839 shares of Monolithic Power Systems, Inc.. This represents a change in shares of -2.51% during the quarter.

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.

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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)
2026-04-23 2026-03-31 13F MONOLITHIC PWR SYS COM 609839105 6,667 -172 -2.51 7,289 17.60 0.0888
2026-02-02 2025-12-31 13F MONOLITHIC PWR SYS COM 609839105 6,839 -166 -2.37 6,199 -3.89 0.0880
2025-11-06 2025-09-30 13F MONOLITHIC PWR SYS COM 609839105 7,005 -233 -3.22 6,449 21.84 0.0787
2025-07-31 2025-06-30 13F MONOLITHIC PWR SYS COM 609839105 7,238 -693 -8.74 5,294 15.09 0.0700
2025-04-23 2025-03-31 13F MONOLITHIC PWR SYS COM 609839105 7,931 3,698 87.36 4,600 83.67 0.0694
2025-02-05 2024-12-31 13F MONOLITHIC PWR SYS COM 609839105 4,233 1,331 45.86 2,505 -6.64 0.0374
2024-11-05 2024-09-30 13F MONOLITHIC PWR SYS COM 609839105 2,902 -998 -25.59 2,683 -16.29 0.0409
2024-08-08 2024-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,900 -818 -17.34 3,205 0.25 0.0509
2024-05-07 2024-03-31 13F MONOLITHIC PWR SYS COM 609839105 4,718 610 14.85 3,196 23.35 0.0530
2024-02-13 2023-12-31 13F MONOLITHIC PWR SYS COM 609839105 4,108 -138 -3.25 2,591 32.13 0.0476
2023-11-08 2023-09-30 13F MONOLITHIC PWR SYS COM 609839105 4,246 261 6.55 1,962 -8.88 0.0405
2023-08-03 2023-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,985 765 23.76 2,153 33.58 0.0431
2023-05-10 2023-03-31 13F MONOLITHIC PWR SYS COM 609839105 3,220 -743 -18.75 1,612 14.99 0.0342
2023-02-08 2022-12-31 13F MONOLITHIC PWR SYS COM 609839105 3,963 373 10.39 1,401 7.36 0.0319
2022-11-14 2022-09-30 13F MONOLITHIC PWR SYS COM 609839105 3,590 -162 -4.32 1,305 -9.44 0.0305
2022-08-08 2022-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,752 757 25.28 1,441 -0.96 0.0310
2022-05-12 2022-03-31 13F MONOLITHIC PWR SYS COM 609839105 2,995 -182 -5.73 1,455 -7.15 0.0262
2022-02-02 2021-12-31 13F MONOLITHIC PWR SYS COM 609839105 3,177 -171 -5.11 1,567 -3.39 0.0274
2021-11-12 2021-09-30 13F MONOLITHIC PWR SYS COM 609839105 3,348 275 8.95 1,622 41.29 0.0304
2021-08-03 2021-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,073 181 6.26 1,148 12.44 0.0206
2021-05-10 2021-03-31 13F MONOLITHIC PWR SYS COM 609839105 2,892 -313 -9.77 1,021 -13.03 0.0204
2021-02-11 2020-12-31 13F MONOLITHIC PWR SYS COM 609839105 3,205 -74 -2.26 1,174 28.03 0.0248
2020-11-13 2020-09-30 13F MONOLITHIC PWR SYS COM 609839105 3,279 -1,609 -32.92 917 -20.81 0.0229
2020-08-11 2020-06-30 13F MONOLITHIC PWR SYS COM 609839105 4,888 -289 -5.58 1,158 33.72 0.0300
2020-05-08 2020-03-31 13F MONOLITHIC PWR SYS COM 609839105 5,177 -980 -15.92 866 -20.99 0.0263
2020-02-07 2019-12-31 13F MONOLITHIC PWR SYS COM 609839105 6,157 855 16.13 1,096 32.85 0.0271
2019-10-31 2019-09-30 13F MONOLITHIC PWR SYS COM 609839105 5,302 -1,198 -18.43 825 -6.46 0.0225
2019-08-09 2019-06-30 13F MONOLITHIC PWR SYS COM 609839105 6,500 696 11.99 882 12.21 0.0240
2019-04-24 2019-03-31 13F MONOLITHIC PWR SYS COM 609839105 5,804 1,579 37.37 786 60.08 0.0210
2019-01-29 2018-12-31 13F MONOLITHIC PWR SYS COM 609839105 4,225 440 11.62 491 3.37 0.0154
2018-10-26 2018-09-30 13F MONOLITHIC PWR SYS COM 609839105 3,785 75 2.02 475 -4.23 0.0121
2018-08-10 2018-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,710 -90 -2.37 496 12.73 0.0135
2018-05-01 2018-03-31 13F MONOLITHIC PWR SYS COM 609839105 3,800 -24 -0.63 440 2.33 0.0113
2018-02-07 2017-12-31 13F MONOLITHIC PWR SYS COM 609839105 3,824 207 5.72 430 11.69 0.0111
2017-11-09 2017-09-30 13F MONOLITHIC PWR SYS COM 609839105 3,617 3,617 385 0.0103
2017-08-09 2017-06-30 13F MONOLITHIC PWR SYS COM 609839105 0 -2,193 -100.00 0 -100.00
2017-05-15 2017-03-31 13F MONOLITHIC PWR SYS COM 609839105 2,193 2,193 202 0.0057
2017-02-01 2016-12-31 13F MONOLITHIC PWR SYS COM 609839105 0 -2,480 -100.00 0 -100.00
2016-11-07 2016-09-30 13F MONOLITHIC PWR SYS COM 609839105 2,480 2,480 200 0.0058
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.