Monolithic Power Systems, Inc.
MX ˙ BMV ˙ US6098391054
SecurityMX:MPWR / Monolithic Power Systems, Inc.
InstitutionSei Investments Co
Latest Disclosed Ownership166,693 shares
Latest Disclosed Value $ 151,085,444
Sei Investments Co reports 16.52% decrease in ownership of MPWR / Monolithic Power Systems, Inc.

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 166,693 shares of Monolithic Power Systems, Inc. (MX:MPWR) valued at $151,085,444 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 199,686 shares of Monolithic Power Systems, Inc.. This represents a change in shares of -16.52% 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)
2026-02-13 2025-12-31 13F MONOLITHIC PWR SYS COM 609839105 166,693 -32,993 -16.52 151,085 -17.82 0.1491
2025-11-13 2025-09-30 13F MONOLITHIC PWR SYS COM 609839105 199,686 199 0.10 183,836 26.00 0.1977
2025-08-14 2025-06-30 13F MONOLITHIC PWR SYS COM 609839105 199,487 -957 -0.48 145,898 25.50 0.1691
2025-05-14 2025-03-31 13F/A-1 MONOLITHIC PWR SYS COM 609839105 200,444 2,028 1.02 116,254 -0.98 0.1496
2025-05-13 2025-03-31 13F MONOLITHIC PWR SYS COM 609839105 201,363 2,947 119,062 0.1295
2025-02-11 2024-12-31 13F MONOLITHIC PWR SYS COM 609839105 198,416 1,300 0.66 117,402 -35.57 0.1508
2024-11-12 2024-09-30 13F MONOLITHIC PWR SYS COM 609839105 197,116 -13,353 -6.34 182,231 5.37 0.2366
2024-08-13 2024-06-30 13F MONOLITHIC PWR SYS COM 609839105 210,469 -41,556 -16.49 172,937 1.30 0.2450
2024-05-07 2024-03-31 13F MONOLITHIC PWR SYS COM 609839105 252,025 -13,308 -5.02 170,726 2.01 0.2501
2024-02-14 2023-12-31 13F MONOLITHIC PWR SYS COM 609839105 265,333 -21,895 -7.62 167,365 26.12 0.2687
2023-11-14 2023-09-30 13F MONOLITHIC PWR SYS COM 609839105 287,228 1,900 0.67 132,698 -13.91 0.2384
2023-08-11 2023-06-30 13F MONOLITHIC PWR SYS COM 609839105 285,328 47,402 19.92 154,142 29.43 0.2689
2023-05-12 2023-03-31 13F MONOLITHIC PWR SYS COM 609839105 237,926 20,965 9.66 119,090 55.23 0.2212
2023-02-10 2022-12-31 13F MONOLITHIC PWR SYS COM 609839105 216,961 12,153 5.93 76,718 3.08 0.1705
2022-11-14 2022-09-30 13F MONOLITHIC PWR SYS COM 609839105 204,808 4,458 2.23 74,427 -3.23 0.1660
2022-08-15 2022-06-30 13F MONOLITHIC PWR SYS COM 609839105 200,350 32,039 19.04 76,909 -5.91 0.1661
2022-05-13 2022-03-31 13F MONOLITHIC PWR SYS COM 609839105 168,311 12,995 8.37 81,737 6.72 0.1643
2022-02-14 2021-12-31 13F MONOLITHIC PWR SYS COM 609839105 155,316 8,920 6.09 76,587 8.04 0.1437
2021-11-12 2021-09-30 13F MONOLITHIC PWR SYS COM 609839105 146,396 100,432 218.50 70,890 314.10 0.1487
2021-08-06 2021-06-30 13F MONOLITHIC PWR SYS COM 609839105 45,964 -10,820 -19.05 17,119 -15.45 0.0380
2021-05-12 2021-03-31 13F MONOLITHIC PWR SYS COM 609839105 56,784 6,852 13.72 20,246 10.71 0.0510
2021-02-08 2020-12-31 13F MONOLITHIC PWR SYS COM 609839105 49,932 -1,991 -3.83 18,288 25.68 0.0473
2020-12-04 2020-09-30 13F/A-1 MONOLITHIC PWR SYS COM 609839105 51,923 5,116 10.93 14,551 31.84 0.0421
2020-11-06 2020-09-30 13F MONOLITHIC PWR SYS COM 609839105 53,656 6,849 15,036 36,203.3449
2020-08-17 2020-06-30 13F/A-1 MONOLITHIC PWR SYS COM 609839105 46,807 -1,550 -3.21 11,037 36.06 0.0343
2020-08-11 2020-06-30 13F MONOLITHIC PWR SYS COM 609839105 39,906 -8,451 7,615 20,656.0928
2020-05-14 2020-03-31 13F MONOLITHIC PWR SYS COM 609839105 48,357 4,941 11.38 8,112 5.50 0.0298
2020-02-06 2019-12-31 13F MONOLITHIC PWR SYS COM 609839105 43,416 1,890 4.55 7,689 18.79 0.0229
2019-11-12 2019-09-30 13F MONOLITHIC PWR SYS COM 609839105 41,526 -3,822 -8.43 6,473 5.23 0.0166
2019-08-14 2019-06-30 13F MONOLITHIC PWR SYS COM 609839105 45,348 3,574 8.56 6,151 8.75 0.0201
2019-05-15 2019-03-31 13F MONOLITHIC PWR SYS COM 609839105 41,774 4,372 11.69 5,656 21.92 0.0190
2019-02-13 2018-12-31 13F MONOLITHIC PWR SYS COM 609839105 37,402 1,594 4.45 4,639 2.72 0.0165
2018-11-08 2018-09-30 13F MONOLITHIC PWR SYS COM 609839105 35,808 -19,293 -35.01 4,516 -38.69 0.0164
2018-08-03 2018-06-30 13F MONOLITHIC PWR SYS COM 609839105 55,101 27,920 102.72 7,366 134.06 0.0250
2018-05-11 2018-03-31 13F MONOLITHIC PWR SYS COM 609839105 27,181 4,263 18.60 3,147 22.21 0.0121
2018-02-08 2017-12-31 13F MONOLITHIC PWR SYS COM 609839105 22,918 635 2.85 2,575 8.42 0.0089
2017-11-06 2017-09-30 13F MONOLITHIC PWR SYS COM 609839105 22,283 6,357 39.92 2,375 54.62 0.0084
2017-07-31 2017-06-30 13F MONOLITHIC PWR SYS COM 609839105 15,926 6,347 66.26 1,536 74.15 0.0061
2017-05-05 2017-03-31 13F MONOLITHIC PWR SYS COM 609839105 9,579 7,363 332.27 882 387.29 0.0039
2017-02-02 2016-12-31 13F MONOLITHIC PWR SYS COM 609839105 2,216 -4,994 -69.26 181 -68.85 0.0009
2016-11-04 2016-09-30 13F MONOLITHIC PWR SYS COM 609839105 7,210 273 3.94 581 22.57 0.0030
2016-08-11 2016-06-30 13F MONOLITHIC PWR SYS COM 609839105 6,937 6,492 1,458.88 474 1,534.48 0.0028
2016-05-10 2016-03-31 13F/A-1 MONOLITHIC PWR SYS COM 609839105 445 -2,133 -82.74 29 -82.32 0.0002
2016-02-03 2015-12-31 13F MONOLITHIC PWR SYS COM 609839105 2,578 1,358 111.31 164 160.32 0.0010
2015-11-02 2015-09-30 13F/A-1 MONOLITHIC PWR SYS COM 609839105 1,220 -43 -3.40 63 -1.56 0.0006
2015-10-30 2015-09-30 13F MONOLITHIC PWR SYS COM 609839105 1,220 63
2015-08-07 2015-06-30 13F/A-1 MONOLITHIC PWR SYS COM 609839105 1,263 663 110.50 64 88.24 0.0006
2015-08-04 2015-06-30 13F MONOLITHIC PWR SYS COM 609839105 1,263 663 64 0.0006
2015-05-14 2015-03-31 13F/A-1 MONOLITHIC PWR SYS COM 609839105 600 522 669.23 34 3,300.00 0.0003
2015-05-01 2015-03-31 13F MONOGRAM RESIDENTIAL TR COM 609839105 600 34
2015-02-10 2014-12-31 13F MONOLITHIC PWR SYS COM 609839105 78 78 1 0.0000
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.