Monolithic Power Systems Inc
Ownership
Ownership Structure
Who owns Monolithic Power Systems Inc (MPWR)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 96.4% of the shares are freely tradable; institutional investors hold 101.1%.
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| BlackRock Inc | 12.36 | 6,072,467 | +1.8 | 03/31/2026 |
| FMR Inc | 8.96 | 4,400,831 | +10.7 | 03/31/2026 |
| Vanguard Capital Management, LLC | 6.27 | 3,083,449 | +0.0 | 03/31/2026 |
| Vanguard Portfolio Management, LLC | 5.12 | 2,516,492 | +0.0 | 03/31/2026 |
| Amvescap Plc. | 5.12 | 2,515,987 | +0.2 | 03/31/2026 |
| State Street Corp | 4.45 | 2,188,454 | +0.4 | 03/31/2026 |
| Geode Capital Management, LLC | 2.91 | 1,432,066 | +3.6 | 03/31/2026 |
Funds
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| Fidelity Select Semiconductors | 3.75 | 1,843,948 | -0.7 | 07/31/2026 |
| Vanguard MStar Total Stk Mkt Idx Invest | 3.02 | 1,486,343 | +0.3 | 07/31/2026 |
| Vanguard 500 Index Investor | 2.63 | 1,290,190 | +1.1 | 07/31/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider holdings
| Person | Role | Shares | Value | As of | Type |
|---|---|---|---|---|---|
| Sciammas Maurice | EVP, WW Sales & Marketing | 188,825 | 220,849,720 $ | Jul 15, 2026 | both |
| Dean Robert W Ii | Interim CFO | 7,089 | 8,291,294 $ | Aug 24, 2026 | direct |
| Tseng Saria | EVP & General Counsel | 2,000 | 2,339,200 $ | Aug 31, 2026 | indirect |
| Chang Kuo Wei Herbert | Director | 515 | 602,344 $ | Aug 24, 2026 | direct |
Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.
Insiders
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Aug 31, 2026 | Tseng Saria | EVP & General Counsel | Other | 2,000 | 0.00 | – |
| Aug 24, 2026 | Dean Robert W Ii | Interim CFO | Other | 5 | 0.00 | – |
| Aug 24, 2026 | Dean Robert W Ii | Interim CFO | Sell | 32 | 1,297.72 | 41,527 |
| Aug 24, 2026 | Chang Kuo Wei Herbert | Director | Sell | 50 | 1,281.57 | 64,079 |
| Aug 17, 2026 | Dean Robert W Ii | Interim CFO | Sell | 6 | 1,413.64 | 8,482 |
| Aug 11, 2026 | Chang Kuo Wei Herbert | Director | Sell | 50 | 1,420.00 | 71,000 |
| Aug 5, 2026 | Dean Robert W Ii | Interim CFO | Sell | 105 | 1,344.27 | 141,148 |
| Aug 4, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Other | 25,000 | 0.00 | – |
| Aug 3, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 30 | 1,343.94 | 40,318 |
| Jul 25, 2026 | Dean Robert W Ii | Interim CFO | Other | 1,359 | 0.00 | – |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 110 | 1,405.71 | 154,628 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 117 | 1,400.45 | 163,853 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 213 | 1,396.16 | 297,382 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 410 | 1,384.11 | 567,485 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 418 | 1,378.73 | 576,309 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 472 | 1,375.47 | 649,222 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 240 | 1,369.18 | 328,603 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 50 | 1,388.19 | 69,410 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 5,640 | 1,352.95 | 7,630,638 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 1,506 | 1,348.91 | 2,031,458 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 1,864 | 1,344.16 | 2,505,514 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 1,460 | 1,339.59 | 1,955,801 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 776 | 1,334.59 | 1,035,642 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 464 | 1,329.30 | 616,795 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 409 | 1,323.93 | 541,487 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 274 | 1,318.42 | 361,247 |
| Jul 15, 2026 | Sciammas Maurice | EVP, WW Sales & Marketing | Sell | 527 | 1,314.03 | 692,494 |
Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character. View all insider transactions →
Data as of: September 17, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)
Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.