Monolithic Power Systems, Inc.
MX ˙ BMV ˙ US6098391054
SecurityMX:MPWR / Monolithic Power Systems, Inc.
InstitutionUBS Group AG
Latest Disclosed Ownership540,413 shares
Latest Disclosed Value $ 590,860,554
UBS Group AG ownership in MPWR / Monolithic Power Systems, Inc.

On May 5, 2026 - UBS Group AG filed a 13F-HR form disclosing ownership of 540,413 shares of Monolithic Power Systems, Inc. (MX:MPWR) valued at $590,860,554 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 29, 2026 disclosing 438,985 shares of Monolithic Power Systems, Inc.. This represents a change in shares of 23.11% during the quarter.

UBS Group AG has a history of taking positions in derivatives of the underlying security (MPWR) in the form of stock options. The firm currently holds call options representing 1,500 of underlying shares valued at $1,640,025 USD and put options representing 0 of underlying shares valued at $0 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.

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Institutional Put/Call Ratios
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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.

MX:MPWR / Monolithic Power Systems, 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)
2026-05-05 2026-03-31 13F MONOLITHIC PWR SYS COM 609839105 540,413 101,428 23.11 590,861 48.50 0.0166
2026-01-29 2025-12-31 13F MONOLITHIC PWR SYS COM 609839105 438,985 -89,334 -16.91 397,878 -18.20 0.0645
2025-11-13 2025-09-30 13F MONOLITHIC PWR SYS COM 609839105 528,319 25,783 5.13 486,392 32.34 0.0762
2025-08-14 2025-06-30 13F MONOLITHIC PWR SYS COM 609839105 502,536 145,246 40.65 367,545 77.37 0.0636
2025-05-13 2025-03-31 13F MONOLITHIC PWR SYS COM 609839105 357,290 -53,282 -12.98 207,221 -14.70 0.0381
2025-02-14 2024-12-31 13F MONOLITHIC PWR SYS COM 609839105 410,572 198,150 93.28 242,935 23.70 0.0449
2024-11-14 2024-09-30 13F MONOLITHIC PWR SYS COM 609839105 212,422 95,244 81.28 196,384 103.97 0.0428
2024-08-14 2024-06-30 13F MONOLITHIC PWR SYS COM 609839105 117,178 -51,357 -30.47 96,283 -15.67 0.0238
2024-05-13 2024-03-31 13F MONOLITHIC PWR SYS COM 609839105 168,535 -25,751 -13.25 114,169 -6.84 0.0284
2024-02-09 2023-12-31 13F MONOLITHIC PWR SYS COM 609839105 194,286 97,357 100.44 122,552 173.67 0.0367
2023-11-09 2023-09-30 13F MONOLITHIC PWR SYS COM 609839105 96,929 9,080 10.34 44,781 -5.64 0.0154
2023-08-11 2023-06-30 13F MONOLITHIC PWR SYS COM 609839105 87,849 -19,038 -17.81 47,459 -11.30 0.0160
2023-05-12 2023-03-31 13F MONOLITHIC PWR SYS COM 609839105 106,887 35,736 50.23 53,501 112.65 0.0196
2023-02-08 2022-12-31 13F MONOLITHIC PWR SYS COM 609839105 71,151 64,098 908.80 25,160 881.62 0.0094
2022-11-10 2022-09-30 13F MONOLITHIC PWR SYS COM 609839105 7,053 -61,558 -89.72 2,563 -90.27 0.0011
2022-08-10 2022-06-30 13F MONOLITHIC PWR SYS COM 609839105 68,611 -32,795 -32.34 26,349 -46.50 0.0108
2022-05-16 2022-03-31 13F MONOLITHIC PWR SYS COM 609839105 101,406 33,456 49.24 49,251 46.92 0.0164
2022-02-14 2021-12-31 13F MONOLITHIC PWR SYS COM 609839105 67,950 -42,632 -38.55 33,522 -37.46 0.0096
2021-11-15 2021-09-30 13F MONOLITHIC PWR SYS COM 609839105 110,582 2,140 1.97 53,597 32.34 0.0169
2021-08-13 2021-06-30 13F MONOLITHIC PWR SYS COM 609839105 108,442 -16,794 -13.41 40,498 -8.45 0.0131
2021-05-12 2021-03-31 13F MONOLITHIC PWR SYS COM 609839105 125,236 97,036 344.10 44,235 328.30 0.0147
2021-02-11 2020-12-31 13F MONOLITHIC PWR SYS COM 609839105 28,200 -73,283 -72.21 10,328 -63.60 0.0035
2020-11-12 2020-09-30 13F MONOLITHIC PWR SYS COM 609839105 101,483 81,223 400.90 28,376 491.04 0.0107
2020-07-31 2020-06-30 13F MONOLITHIC PWR SYS COM 609839105 20,260 -32,313 -61.46 4,801 -45.47 0.0020
2020-05-01 2020-03-31 13F MONOLITHIC PWR SYS COM 609839105 52,573 -39,478 -42.89 8,804 -46.27 0.0041
2020-02-14 2019-12-31 13F MONOLITHIC PWR SYS COM 609839105 92,051 75,726 463.87 16,387 544.90 0.0057
2019-11-14 2019-09-30 13F MONOLITHIC PWR SYS COM 609839105 16,325 -26,375 -61.77 2,541 -56.17 0.0010
2019-08-14 2019-06-30 13F MONOLITHIC PWR SYS COM 609839105 42,700 17,617 70.23 5,798 70.58 0.0022
2019-05-14 2019-03-31 13F MONOLITHIC PWR SYS COM 609839105 25,083 -5,140 -17.01 3,399 -3.25 0.0014
2019-02-14 2018-12-31 13F MONOLITHIC PWR SYS COM 609839105 30,223 -25,338 -45.60 3,513 -49.63 0.0016
2018-11-14 2018-09-30 13F MONOLITHIC PWR SYS COM 609839105 55,561 -18,194 -24.67 6,975 -29.25 0.0028
2018-08-14 2018-06-30 13F MONOLITHIC PWR SYS COM 609839105 73,755 44,711 153.94 9,859 193.25 0.0043
2018-05-15 2018-03-31 13F MONOLITHIC PWR SYS COM 609839105 29,044 15,521 114.77 3,362 121.33 0.0015
2018-02-14 2017-12-31 13F MONOLITHIC PWR SYS COM 609839105 13,523 -1,816 -11.84 1,519 -7.04 0.0006
2017-11-14 2017-09-30 13F MONOLITHIC PWR SYS COM 609839105 15,339 2,686 21.23 1,634 34.04 0.0008
2017-11-14 2017-06-30 13F/A-1 MONOLITHIC PWR SYS COM 609839105 12,653 -25,424 -66.77 1,219 -65.24 0.0006
2017-08-14 2017-06-30 13F MONOLITHIC PWR SYS COM 609839105 12,653 -25,424 1,219
2017-11-14 2017-03-31 13F/A-1 MONOLITHIC PWR SYS COM 609839105 38,077 12,848 50.93 3,507 69.67 0.0019
2017-05-12 2017-03-31 13F MONOLITHIC PWR SYS COM 609839105 38,077 12,848 3,507
2017-02-14 2016-12-31 13F MONOLITHIC PWR SYS COM 609839105 25,229 16,074 175.58 2,067 180.46 0.0011
2016-11-14 2016-09-30 13F MONOLITHIC PWR SYS COM 609839105 9,155 5,569 155.30 737 200.82 0.0004
2016-08-12 2016-06-30 13F MONOLITHIC PWR SYS COM 609839105 3,586 -15,116 -80.83 245 -79.41 0.0002
2016-05-12 2016-03-31 13F MONOLITHIC PWR SYS COM 609839105 18,702 15,051 412.24 1,190 412.93 0.0008
2016-02-16 2015-12-31 13F MONOLITHIC PWR SYS COM 609839105 3,651 295 8.79 232 34.88 0.0002
2015-11-13 2015-09-30 13F MONOLITHIC PWR SYS COM 609839105 3,356 708 26.74 172 28.36 0.0001
2015-08-14 2015-06-30 13F MONOLITHIC PWR SYS COM 609839105 2,648 -6,349 -70.57 134 -71.73 0.0001
2015-05-14 2015-03-31 13F MONOLITHIC PWR SYS COM 609839105 8,997 -5,054 -35.97 474 -32.19 0.0003
2015-02-17 2014-12-31 13F MONOLITHIC PWR SYS COM 609839105 14,051 14,051 699 0.0005
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
(%)
2026-05-05 2026-03-31 13F MONOLITHIC PWR SYS COM Call 1,500 1,640 n/a n/a n/a
2025-08-14 2025-06-30 13F MONOLITHIC PWR SYS COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2025-05-13 2025-03-31 13F MONOLITHIC PWR SYS COM Call 18,000 10,440 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
(%)
2025-08-14 2025-06-30 13F MONOLITHIC PWR SYS COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2025-05-13 2025-03-31 13F MONOLITHIC PWR SYS COM Put 18,000 10,440 n/a n/a n/a
2015-05-14 2015-03-31 13F MONOLITHIC PWR SYS COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2015-02-17 2014-12-31 13F MONOLITHIC PWR SYS COM Put 100 5 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.