MPWR insider buying and SEC filings, explained
Monolithic Power Systems Inc. · CIK 1280452
Tracked: Forms 3/4/5, 8-K, NT · All filings on sec.gov
Insider activity in the last 12 months
Bought
$0
Insiders who bought
0
Sold (not marked 10b5-1)
$469.3M
Planned sales (10b5-1)
$258.5M
Insider purchases and sales, last 12 months
| Traded | Type | What was filed | Source |
|---|---|---|---|
| Sep 28, 2026 | Planned (10b5-1) | Michael Hsing (CEO and Director) sold 30,000 shares at about $1,344.97 ($40.3M), marked as a 10b5-1 plan trade. Holdings down 4% to 818,264 shares. | SEC filing Filed Sep 30, 2026 |
| Aug 24, 2026 | Sale | Robert W. Dean II (CFO) sold 32 shares at about $1,297.72 ($42K). Holdings down <1% to 7,094 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 26, 2026 |
| Aug 24, 2026 | Sale | Kuo Wei Herbert Chang (Director) sold 50 shares at $1,281.57 ($64K). Holdings down 9% to 515 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 25, 2026 |
| Aug 17, 2026 | Sale | Robert W. Dean II (CFO) sold 6 shares at $1,413.64 ($8K). Holdings down <1% to 7,126 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 19, 2026 |
| Aug 11, 2026 | Sale | Kuo Wei Herbert Chang (Director) sold 50 shares at $1,420.00 ($71K). Holdings down 8% to 565 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 13, 2026 |
| Aug 5, 2026 | Sale | Robert W. Dean II (CFO) sold 105 shares at $1,344.27 ($141K). Holdings down 1% to 7,132 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 6, 2026 |
| Aug 3, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 30 shares indirectly (by trust) at $1,343.94 ($40K), marked as a 10b5-1 plan trade. Holdings by trust down 3% to 1,119 shares. | SEC filing Filed Aug 5, 2026 |
| Jul 15, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 15,000 shares at about $1,349.73 ($20.2M), marked as a 10b5-1 plan trade. Holdings down 9% to 151,644 shares. | SEC filing Filed Jul 17, 2026 |
| Jul 1, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 30 shares indirectly (by trust) at $1,351.61 ($41K), marked as a 10b5-1 plan trade. Holdings by trust down 3% to 1,149 shares. | SEC filing Filed Jul 6, 2026 |
| Jun 1, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 30 shares indirectly (by trust) at $1,533.95 ($46K), marked as a 10b5-1 plan trade. Holdings by trust down 2% to 1,179 shares. | SEC filing Filed Jun 3, 2026 |
| May 27, 2026 | Sale | Saria Tseng (EVP & General Counsel) sold 7,565 shares at $1,700.00 ($12.9M). Holdings down 5% to 144,218 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 29, 2026 |
| May 26, 2026 | Sale | Robert W. Dean II (CFO) sold 22 shares at about $1,649.56 ($36K). Holdings down <1% to 5,878 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 28, 2026 |
| May 26, 2026 | Sale | Jeff Zhou (Director) sold 486 shares at $1,680.00 ($816K). Holdings down 11% to 3,800 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 27, 2026 |
| May 22, 2026 | Sale | Saria Tseng (EVP & General Counsel) sold 5,000 shares at $1,586.43 ($7.9M). Holdings down 3% to 151,783 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 27, 2026 |
| May 18, 2026 | Sale | Michael Hsing (CEO and Director) sold 40,000 shares at about $1,482.75 ($59.3M). Holdings down 5% to 848,263 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 20, 2026 |
| May 18, 2026 | Sale | Robert W. Dean II (CFO) sold 4 shares at $1,563.28 ($6K). Holdings down <1% to 5,900 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 20, 2026 |
| May 15, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 12,000 shares at about $1,561.40 ($18.7M), marked as a 10b5-1 plan trade. Holdings down 7% to 166,644 shares. | SEC filing Filed May 19, 2026 |
| May 6, 2026 | Sale | Eugen J Elmiger (Director) sold 12,000 shares at about $1,584.96 ($19.0M). Holdings down 69% to 5,402 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 8, 2026 |
| May 6, 2026 | Sale | Deming Xiao (EVP, Global Operations) sold 30,000 shares at about $1,654.55 ($49.6M). Holdings down 13% to 205,959 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 8, 2026 |
| May 6, 2026 | Sale | Eileen Wynne (Director) sold 335 shares at $1,582.68 ($530K). Holdings down 25% to 1,007 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 8, 2026 |
| May 5–6, 2026 | Sale | Jeff Zhou (Director) sold 1,514 shares between May 5 and May 6 at about $1,607.85 ($2.4M). Holdings down 26% to 4,286 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 6, 2026 |
| May 5, 2026 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 380 shares indirectly at $1,583.81 ($602K). Indirect holdings down 29% to 919 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 6, 2026 |
| May 4, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 30 shares indirectly (by trust) at $1,588.73 ($48K), marked as a 10b5-1 plan trade. Holdings by trust down 2% to 1,209 shares. | SEC filing Filed May 6, 2026 |
| Apr 8, 2026 | Planned (10b5-1) | Saria Tseng (EVP & General Counsel) sold 8,963 shares at about $1,305.22 ($11.7M), marked as a 10b5-1 plan trade. Holdings down 5% to 156,983 shares. | SEC filing Filed Apr 10, 2026 |
| Apr 6, 2026 | Planned (10b5-1) | Saria Tseng (EVP & General Counsel) sold 7,636 shares at about $1,167.95 ($8.9M), marked as a 10b5-1 plan trade. Holdings down 4% to 165,946 shares. | SEC filing Filed Apr 8, 2026 |
| Apr 1, 2026 | Planned (10b5-1) | Saria Tseng (EVP & General Counsel) sold 1,400 shares at about $1,133.52 ($1.6M), marked as a 10b5-1 plan trade. Holdings down 1% to 173,582 shares. | SEC filing Filed Apr 3, 2026 |
| Apr 1, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 30 shares indirectly (by trust) at $1,116.44 ($33K), marked as a 10b5-1 plan trade. Holdings by trust down 2% to 1,239 shares. | SEC filing Filed Apr 3, 2026 |
| Mar 30, 2026 | Planned (10b5-1) | Saria Tseng (EVP & General Counsel) sold 25,674 shares at about $1,010.50 ($25.9M), marked as a 10b5-1 plan trade. Holdings down 13% to 174,982 shares. | SEC filing Filed Apr 1, 2026 |
| Mar 20, 2026 | Planned (10b5-1) | Maurice Sciammas (EVP, WW Sales & Marketing) sold 30 shares indirectly (by trust) at about $1,095.07 ($33K), marked as a 10b5-1 plan trade. Holdings by trust down 2% to 1,269 shares. | SEC filing Filed Mar 24, 2026 |
| Feb 12, 2026 | Planned (10b5-1) | Michael Hsing (CEO and Director) sold 33,000 shares at about $1,171.83 ($38.7M), marked as a 10b5-1 plan trade. Holdings down 4% to 888,234 shares. | SEC filing Filed Feb 17, 2026 |
| Feb 11, 2026 | Planned (10b5-1) | Michael Hsing (CEO and Director) sold 33,000 shares at about $1,188.92 ($39.2M), marked as a 10b5-1 plan trade. Holdings down 3% to 921,234 shares. | SEC filing Filed Feb 13, 2026 |
| Feb 11, 2026 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 200 shares indirectly (by trust) at $1,179.98 ($236K). Holdings by trust down 13% to 1,299 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 12, 2026 |
| Feb 10, 2026 | Planned (10b5-1) | Michael Hsing (CEO and Director) sold 34,000 shares at about $1,142.28 ($38.8M), marked as a 10b5-1 plan trade. Holdings down 3% to 954,234 shares. | SEC filing Filed Feb 12, 2026 |
| Feb 9, 2026 | Planned (10b5-1) | Victor K Lee (Director) sold 400 shares at $1,212.16 ($485K), marked as a 10b5-1 plan trade. Holdings down 1% to 27,756 shares. | SEC filing Filed Feb 11, 2026 |
| Feb 6, 2026 | Sale | Deming Xiao (EVP, Global Operations) sold 22,875 shares at $1,171.16 ($26.8M). Holdings down 9% to 235,932 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 10, 2026 |
| Feb 6, 2026 | Sale | Saria Tseng (EVP & General Counsel) sold 22,875 shares at $1,171.16 ($26.8M). Holdings down 10% to 200,626 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 10, 2026 |
| Feb 6, 2026 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 22,875 shares at $1,171.16 ($26.8M). Holdings down 11% to 178,625 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 10, 2026 |
| Feb 6, 2026 | Sale | Theodore Blegen (CFO) sold 21,725 shares at $1,171.16 ($25.4M). Holdings down 21% to 82,353 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 10, 2026 |
| Feb 6, 2026 | Sale | Michael Hsing (CEO and Director) sold 54,923 shares at $1,171.16 ($64.3M). Holdings down 5% to 988,234 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 10, 2026 |
| Feb 2, 2026 | Planned (10b5-1) | Theodore Blegen (CFO) sold 3,000 shares at about $1,129.76 ($3.4M), marked as a 10b5-1 plan trade. Holdings down 4% to 65,333 shares. | SEC filing Filed Feb 4, 2026 |
| Jan 2, 2026 | Planned (10b5-1) | Victor K Lee (Director) sold 600 shares at $930.86 ($559K), marked as a 10b5-1 plan trade. Holdings down 2% to 27,967 shares. | SEC filing Filed Jan 6, 2026 |
| Jan 2, 2026 | Planned (10b5-1) | Theodore Blegen (CFO) sold 3,000 shares at about $940.47 ($2.8M), marked as a 10b5-1 plan trade. Holdings down 4% to 68,332 shares. | SEC filing Filed Jan 6, 2026 |
| Dec 24, 2025 | Planned (10b5-1) | Victor K Lee (Director) sold 1,000 shares at about $951.72 ($952K), marked as a 10b5-1 plan trade. Holdings down 3% to 28,567 shares. | SEC filing Filed Dec 29, 2025 |
| Dec 1, 2025 | Planned (10b5-1) | Theodore Blegen (CFO) sold 3,000 shares at about $908.21 ($2.7M), marked as a 10b5-1 plan trade. Holdings down 4% to 71,332 shares. | SEC filing Filed Dec 2, 2025 |
| Nov 26, 2025 | Sale | Saria Tseng (EVP & General Counsel) sold 20,000 shares at about $926.47 ($18.5M). Holdings down 11% to 167,331 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 28, 2025 |
| Nov 25, 2025 | Sale | Saria Tseng (EVP & General Counsel) sold 20,000 shares at about $904.18 ($18.1M). Holdings down 10% to 187,331 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 28, 2025 |
| Nov 25, 2025 | Sale | Kuo Wei Herbert Chang (Director) sold 100 shares at $896.97 ($90K). Holdings down 19% to 426 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 25, 2025 |
| Nov 24, 2025 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 3,976 shares at $895.23 ($3.6M). Holdings down 3% to 144,330 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 25, 2025 |
| Nov 21, 2025 | Sale | Kuo Wei Herbert Chang (Director) sold 100 shares at $873.97 ($87K). Holdings down 16% to 526 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 24, 2025 |
| Nov 19, 2025 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 27,966 shares at about $881.66 ($24.7M). Holdings down 16% to 148,306 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 20, 2025 |
| Nov 19, 2025 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 7,034 shares at about $870.21 ($6.1M). Holdings down 4% to 176,272 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 20, 2025 |
| Nov 12, 2025 | Sale | Michael Hsing (CEO and Director) sold 37,000 shares at about $965.52 ($35.7M). Holdings down 4% to 918,669 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 13, 2025 |
| Nov 11, 2025 | Sale | Michael Hsing (CEO and Director) sold 40,000 shares at about $958.39 ($38.3M). Holdings down 4% to 955,669 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 13, 2025 |
| Nov 5, 2025 | Sale | Maurice Sciammas (EVP, WW Sales & Marketing) sold 200 shares indirectly at $986.81 ($197K). Indirect holdings down 13% to 1,299 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 6, 2025 |
| Nov 3, 2025 | Planned (10b5-1) | Theodore Blegen (CFO) sold 3,000 shares at about $1,024.43 ($3.1M), marked as a 10b5-1 plan trade. Holdings down 4% to 74,332 shares. | SEC filing Filed Nov 4, 2025 |
22 routine transactions (such as grants, option exercises or tax withholding) are not listed.
Cluster buys
No cluster buys in the last 12 months.
Red flags
No red flags in the last 12 months.
Key events
No key events in the last 12 months.
8-K filings, last 12 months
No 8-K filings in the last 12 months.
Red flags are objective triggers only: the item or form filed, never an opinion.
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