Monolithic Power Systems, Inc.
US ˙ NasdaqGS ˙ US6098391054

SecurityMPWR / Monolithic Power Systems, Inc.
InstitutionWalleye Capital LLC
Latest Disclosed Ownership293 shares
Latest Disclosed Value $ 320,352
Walleye Capital LLC ownership in MPWR / Monolithic Power Systems, Inc.

On May 13, 2026 - Walleye Capital LLC filed a 13F-HR/A form disclosing ownership of 293 shares of Monolithic Power Systems, Inc. (US:MPWR) valued at $320,352 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 188 shares of Monolithic Power Systems, Inc.. This represents a change in shares of 55.85% during the quarter. The current value of the position is $495,138 USD.

Walleye Capital LLC 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 100 of underlying shares valued at $109,335 USD and put options representing 1,100 of underlying shares valued at $1,202,685 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.

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)
2026-05-13 2026-03-31 13F/A-1 MONOLITHIC PWR SYS COM 609839105 293 105 55.85 320 88.24 0.0013
2026-05-08 2026-03-31 13F MONOLITHIC PWR SYS COM 609839105 293 105 320 0.0013
2026-02-13 2025-12-31 13F MONOLITHIC PWR SYS COM 609839105 188 -4,942 -96.34 170 -96.40 0.0005
2025-11-14 2025-09-30 13F MONOLITHIC PWR SYS COM 609839105 5,130 4,197 449.84 4,723 592.38 0.0177
2025-08-13 2025-06-30 13F MONOLITHIC PWR SYS COM 609839105 933 875 1,508.62 682 1,966.67 0.0027
2025-05-14 2025-03-31 13F MONOLITHIC PWR SYS COM 609839105 58 -16,317 -99.65 34 -99.66 0.0002
2025-02-13 2024-12-31 13F MONOLITHIC PWR SYS COM 609839105 16,375 9,522 138.95 9,689 52.94 0.0237
2024-11-14 2024-09-30 13F MONOLITHIC PWR SYS COM 609839105 6,853 5,843 578.51 6,336 664.17 0.0132
2024-08-14 2024-06-30 13F MONOLITHIC PWR SYS COM 609839105 1,010 -89 -8.10 830 11.42 0.0015
2024-05-15 2024-03-31 13F MONOLITHIC PWR SYS COM 609839105 1,099 1,099 744 0.0013
2023-08-14 2023-06-30 13F MONOLITHIC PWR SYS COM 609839105 0 -2,406 -100.00 0 -100.00
2023-05-15 2023-03-31 13F MONOLITHIC PWR SYS COM 609839105 2,406 -7,884 -76.62 1,204 -66.90 0.0180
2023-02-14 2022-12-31 13F MONOLITHIC PWR SYS COM 609839105 10,290 10,290 3,639 0.0664
2022-11-14 2022-09-30 13F MONOLITHIC PWR SYS COM 609839105 0 -2,331 -100.00 0 -100.00
2022-08-19 2022-06-30 13F/A-1 MONOLITHIC PWR SYS COM 609839105 2,331 2,331 895 0.0247
2022-08-08 2022-06-30 13F MONOLITHIC PWR SYS COM 609839105 2,331 2,331 895 0.0247
2019-08-14 2019-03-31 13F/A-1 MONOLITHIC PWR SYS COM 609839105 0 -9,604 -100.00 0 -100.00
2018-11-14 2018-09-30 13F MONOLITHIC PWR SYS COM 609839105 9,604 9,604 1,206 0.5628
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
(%)
2026-05-13 2026-03-31 13F/A MONOLITHIC PWR SYS COM Call 100 -85.71 109 -82.81 n/a n/a n/a
2026-05-08 2026-03-31 13F MONOLITHIC PWR SYS COM Call 100 109 n/a n/a n/a
2026-02-13 2025-12-31 13F MONOLITHIC PWR SYS COM Call 700 -36.36 634 -37.35 n/a n/a n/a
2025-11-14 2025-09-30 13F MONOLITHIC PWR SYS COM Call 1,100 22.22 1,013 53.80 n/a n/a n/a
2025-08-13 2025-06-30 13F MONOLITHIC PWR SYS COM Call 900 -50.00 658 -36.91 n/a n/a n/a
2025-05-14 2025-03-31 13F MONOLITHIC PWR SYS COM Call 1,800 -41.94 1,044 -43.13 n/a n/a n/a
2025-02-13 2024-12-31 13F MONOLITHIC PWR SYS COM Call 3,100 1,834 n/a n/a n/a
2024-11-14 2024-09-30 13F MONOLITHIC PWR SYS COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2024-08-14 2024-06-30 13F MONOLITHIC PWR SYS COM Call 200 -89.47 164 -87.26 n/a n/a n/a
2024-05-15 2024-03-31 13F MONOLITHIC PWR SYS COM Call 1,900 171.43 1,287 191.84 n/a n/a n/a
2024-02-14 2023-12-31 13F MONOLITHIC PWR SYS COM Call 700 -69.57 442 -58.47 n/a n/a n/a
2023-11-21 2023-09-30 13F/A MONOLITHIC PWR SYS COM Call 2,300 64.29 1,063 40.48 n/a n/a n/a
2023-11-14 2023-09-30 13F MONOLITHIC PWR SYS COM Call 2,300 1,063 n/a n/a n/a
2023-08-14 2023-06-30 13F MONOLITHIC PWR SYS COM Call 1,400 180.00 756 202.40 n/a n/a n/a
2023-05-15 2023-03-31 13F MONOLITHIC PWR SYS COM Call 500 250 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
(%)
2026-05-13 2026-03-31 13F/A MONOLITHIC PWR SYS COM Put 1,100 -62.07 1,203 -54.26 n/a n/a n/a
2026-05-08 2026-03-31 13F MONOLITHIC PWR SYS COM Put 1,100 1,203 n/a n/a n/a
2026-02-13 2025-12-31 13F MONOLITHIC PWR SYS COM Put 2,900 7.41 2,628 5.75 n/a n/a n/a
2025-11-14 2025-09-30 13F MONOLITHIC PWR SYS COM Put 2,700 8.00 2,486 35.94 n/a n/a n/a
2025-08-13 2025-06-30 13F MONOLITHIC PWR SYS COM Put 2,500 -43.18 1,828 -28.34 n/a n/a n/a
2025-05-14 2025-03-31 13F MONOLITHIC PWR SYS COM Put 4,400 -8.33 2,552 -10.18 n/a n/a n/a
2025-02-13 2024-12-31 13F MONOLITHIC PWR SYS COM Put 4,800 84.62 2,840 18.19 n/a n/a n/a
2024-11-14 2024-09-30 13F MONOLITHIC PWR SYS COM Put 2,600 85.71 2,404 108.96 n/a n/a n/a
2024-08-14 2024-06-30 13F MONOLITHIC PWR SYS COM Put 1,400 -75.86 1,150 -70.73 n/a n/a n/a
2024-05-15 2024-03-31 13F MONOLITHIC PWR SYS COM Put 5,800 205.26 3,929 227.96 n/a n/a n/a
2024-02-14 2023-12-31 13F MONOLITHIC PWR SYS COM Put 1,900 -17.39 1,198 12.81 n/a n/a n/a
2023-11-21 2023-09-30 13F/A MONOLITHIC PWR SYS COM Put 2,300 53.33 1,063 31.11 n/a n/a n/a
2023-11-14 2023-09-30 13F MONOLITHIC PWR SYS COM Put 2,300 1,063 n/a n/a n/a
2023-08-14 2023-06-30 13F MONOLITHIC PWR SYS COM Put 1,500 275.00 810 305.00 n/a n/a n/a
2023-05-15 2023-03-31 13F MONOLITHIC PWR SYS COM Put 400 200 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.