Monolithic Power Systems, Inc.
MX ˙ BMV ˙ US6098391054
SecurityMX:MPWR / Monolithic Power Systems, Inc.
InstitutionAsset Management One Co., Ltd.
Latest Disclosed Ownership21,157 shares
Latest Disclosed Value $ 23,132,006
Asset Management One Co., Ltd. reports 1.47% decrease in ownership of MPWR / Monolithic Power Systems, Inc.

On May 8, 2026 - Asset Management One Co., Ltd. filed a 13F-HR form disclosing ownership of 21,157 shares of Monolithic Power Systems, Inc. (MX:MPWR) valued at $23,132,006 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 27, 2026 disclosing 21,473 shares of Monolithic Power Systems, Inc.. This represents a change in shares of -1.47% 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)
2026-05-08 2026-03-31 13F MONOLITHIC PWR SYS COM 609839105 21,157 -316 -1.47 23,132 15.87 0.0682
2026-01-27 2025-12-31 13F MONOLITHIC PWR SYS COM 609839105 21,473 683 3.29 19,963 4.30 0.0555
2025-10-22 2025-09-30 13F MONOLITHIC PWR SYS COM 609839105 20,790 -678 -3.16 19,140 21.90 0.0555
2025-07-31 2025-06-30 13F MONOLITHIC PWR SYS COM 609839105 21,468 714 3.44 15,701 30.45 0.0492
2025-04-23 2025-03-31 13F MONOLITHIC PWR SYS COM 609839105 20,754 242 1.18 12,037 -4.23 0.0416
2025-01-30 2024-12-31 13F MONOLITHIC PWR SYS COM 609839105 20,512 1,034 5.31 12,568 -30.21 0.0432
2024-10-30 2024-09-30 13F MONOLITHIC PWR SYS COM 609839105 19,478 153 0.79 18,007 13.41 0.0641
2024-07-18 2024-06-30 13F MONOLITHIC PWR SYS COM 609839105 19,325 -133 -0.68 15,879 20.46 0.0607
2024-05-02 2024-03-31 13F MONOLITHIC PWR SYS COM 609839105 19,458 196 1.02 13,181 8.25 0.0508
2024-01-24 2023-12-31 13F MONOLITHIC PWR SYS COM 609839105 19,262 -245 -1.26 12,178 35.12 0.0490
2023-10-19 2023-09-30 13F MONOLITHIC PWR SYS COM 609839105 19,507 270 1.40 9,012 -13.28 0.0401
2023-07-31 2023-06-30 13F MONOLITHIC PWR SYS COM 609839105 19,237 -1,771 -8.43 10,392 -1.17 0.0440
2023-04-25 2023-03-31 13F MONOLITHIC PWR SYS COM 609839105 21,008 -674 -3.11 10,515 37.24 0.0477
2023-02-06 2022-12-31 13F MONOLITHIC PWR SYS COM 609839105 21,682 -2,047 -8.63 7,663 -11.14 0.0373
2022-11-04 2022-09-30 13F MONOLITHIC PWR SYS COM 609839105 23,729 -2,013 -7.82 8,623 -12.77 0.0439
2022-07-29 2022-06-30 13F MONOLITHIC PWR SYS COM 609839105 25,742 -796 -3.00 9,885 -23.31 0.0464
2022-05-13 2022-03-31 13F MONOLITHIC PWR SYS COM 609839105 26,538 373 1.43 12,889 -1.12 0.0503
2022-02-09 2021-12-31 13F MONOLITHIC PWR SYS COM 609839105 26,165 2,099 8.72 13,035 11.75 0.0454
2021-11-02 2021-09-30 13F MONOLITHIC PWR SYS COM 609839105 24,066 451 1.91 11,664 32.26 0.0447
2021-08-03 2021-06-30 13F MONOLITHIC PWR SYS COM 609839105 23,615 4,373 22.73 8,819 29.77 0.0328
2021-05-14 2021-03-31 13F MONOLITHIC PWR SYS COM 609839105 19,242 -974 -4.82 6,796 -4.66 0.0270
2021-02-12 2020-12-31 13F MONOLITHIC PWR SYS COM 609839105 20,216 20,216 7,128 0.0294
2020-05-14 2020-03-31 13F MONOLITHIC PWR SYS COM 609839105 0 -2,580 -100.00 0 -100.00
2020-02-14 2019-12-31 13F MONOLITHIC PWR SYS COM 609839105 2,580 -1,970 -43.30 459 -35.26 0.0021
2019-11-14 2019-09-30 13F MONOLITHIC PWR SYS COM 609839105 4,550 -3,999 -46.78 709 -38.93 0.0034
2019-08-14 2019-06-30 13F MONOLITHIC PWR SYS COM 609839105 8,549 -3,879 -31.21 1,161 -31.06 0.0057
2019-05-15 2019-03-31 13F MONOLITHIC PWR SYS COM 609839105 12,428 -4,448 -26.36 1,684 -13.33 0.0091
2019-02-13 2018-12-31 13F MONOLITHIC PWR SYS COM 609839105 16,876 0 0.00 1,943 -8.74 0.0046
2018-11-14 2018-09-30 13F MONOLITHIC PWR SYS COM 609839105 16,876 -13,651 -44.72 2,129 -48.11 0.0044
2018-08-14 2018-06-30 13F MONOLITHIC PWR SYS COM 609839105 30,527 24,638 418.37 4,103 501.61 0.0090
2018-05-14 2018-03-31 13F MONOLITHIC PWR SYS COM 609839105 5,889 5,889 682 0.0015
2018-02-14 2017-12-31 13F MONOLITHIC PWR SYS COM 609839105 0 -4,180 -100.00 0 -100.00
2017-11-14 2017-09-30 13F MONOLITHIC PWR SYS COM 609839105 4,180 451 12.09 445 23.27 0.0010
2017-08-14 2017-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,729 -1,249 -25.09 361 -21.18 0.0009
2017-05-11 2017-03-31 13F MONOLITHIC PWR SYS COM 609839105 4,978 -1,978 -28.44 458 -20.49 0.0012
2017-05-02 2016-12-31 13F/A-1 MONOLITHIC POWER SYSTEMS COM 609839105 6,956 250 3.73 576 8.27 0.0015
2017-02-13 2016-12-31 13F MONOLITHIC POWER SYSTEMS COM 609839105 6,956 576
2016-11-07 2016-09-30 13F MONOLITHIC POWER SYSTEMS Com 609839105 6,706 -1,360 -16.86 532 -1.85 0.0079
2016-08-03 2016-06-30 13F MONOLITHIC POWER SYSTEMS Com 609839105 8,066 -1,946 -19.44 542 -13.69 0.0081
2016-05-05 2016-03-31 13F MONOLITHIC POWER SYSTEMS Com 609839105 10,012 -710 -6.62 628 -9.64 0.0092
2016-01-28 2015-12-31 13F MONOLITHIC POWER SYSTEMS Com 609839105 10,722 -461 -4.12 695 24.11 0.0104
2015-11-12 2015-09-30 13F MONOLITHIC POWER SYSTEMS Com 609839105 11,183 -165 -1.45 560 -2.78 0.0085
2015-08-06 2015-06-30 13F MONOLITHIC POWER SYSTEMS Com 609839105 11,348 -469 -3.97 576 -8.13 0.0080
2015-05-11 2015-03-31 13F MONOLITHIC POWER SYSTEMS COM 609839105 11,817 -715 -5.71 627 0.32 0.0077
2015-02-09 2014-12-31 13F MONOLITHIC POWER SYSTEMS COM 609839105 12,532 -928 -6.89 625 4.52 0.0081
2014-11-05 2014-09-30 13F MONOLITHIC POWER SYSTEMS COM 609839105 13,460 13,460 598 0.0083
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.