Monolithic Power Systems insider activity
What the executives and directors of Monolithic Power Systems actually did with their own shares, decoded from their SEC Form 4 filings. Each figure says the stretch of time it covers.
−$723M
net open-market flow, 12 m
0 open-market buys, 12 m
35.1%
of sale value on 10b5-1 plans, 12 m
– no insider buy on record
The tape: three years of insider trades
Open-market buy
Discretionary sale
Planned sale (10b5-1)
Reported-price path
Routine
Every marker sits at the price reported on the Form 4. The line is the monthly median of all prices insiders reported, so the chart needs no market feed; the grey strip is the routine flow (grants, vestings, tax withholding and gifts) that a headline gets wrong by counting it as selling.
The 59 routine events on the chart, as a list
| Date | Insider | Shares |
|---|---|---|
| Aug 31, 2026 | Tseng Saria | 4,000 |
| Aug 4, 2026 | Sciammas Maurice | 50K |
| Jul 25, 2026 | DEAN ROBERT W II | 1,359 |
| May 29, 2026 | Sciammas Maurice | 12K |
| May 22, 2026 | Tseng Saria | 200 |
| May 13, 2026 | Sciammas Maurice | 3,126 |
| Feb 3, 2026 | CHANG KUO WEI HERBERT | 189 |
| Feb 3, 2026 | Lee Victor K | 189 |
| Feb 3, 2026 | Xiao Deming | 57K |
| Feb 3, 2026 | Hsing Michael | 137K |
| Feb 3, 2026 | Tseng Saria | 57K |
| Feb 3, 2026 | Sciammas Maurice | 57K |
| Feb 3, 2026 | BLEGEN THEODORE | 39K |
| Feb 3, 2026 | Zhou Jeff | 189 |
| Feb 3, 2026 | Elmiger Eugen J | 189 |
| Feb 3, 2026 | Wynne Eileen | 189 |
| Feb 3, 2026 | Martinez Carintia | 189 |
| Dec 24, 2025 | Tseng Saria | 2,000 |
| Dec 9, 2025 | Hsing Michael | 12K |
| Nov 13, 2025 | Sciammas Maurice | 9,060 |
| Oct 30, 2025 | Xiao Deming | 55K |
| Oct 30, 2025 | Hsing Michael | 122K |
| Oct 30, 2025 | Tseng Saria | 55K |
| Oct 30, 2025 | Sciammas Maurice | 55K |
| Oct 30, 2025 | BLEGEN THEODORE | 48K |
| Oct 25, 2025 | Xiao Deming | 136K |
| Oct 25, 2025 | Hsing Michael | 303K |
| Oct 25, 2025 | Tseng Saria | 136K |
| Oct 25, 2025 | Sciammas Maurice | 136K |
| Oct 25, 2025 | BLEGEN THEODORE | 88K |
| Aug 19, 2025 | Sciammas Maurice | 3,998 |
| Aug 11, 2025 | Xiao Deming | 1,890 |
| Aug 6, 2025 | Sciammas Maurice | 8,254 |
| May 28, 2025 | Sciammas Maurice | 2,998 |
| May 9, 2025 | Sciammas Maurice | 3,756 |
| Feb 18, 2025 | Sciammas Maurice | 2,204 |
| Feb 11, 2025 | Sciammas Maurice | 7,575 |
| Feb 4, 2025 | CHANG KUO WEI HERBERT | 335 |
| Feb 4, 2025 | Lee Victor K | 335 |
| Feb 4, 2025 | Zhou Jeff | 335 |
| Feb 4, 2025 | Elmiger Eugen J | 335 |
| Feb 4, 2025 | Wynne Eileen | 335 |
| Feb 4, 2025 | Martinez Carintia | 335 |
| Aug 29, 2024 | Moyer James C | 12K |
| Aug 22, 2024 | Xiao Deming | 79K |
| Aug 8, 2024 | Moyer James C | 22K |
| May 13, 2024 | Sciammas Maurice | 8,554 |
| May 10, 2024 | Xiao Deming | 29 |
| Apr 1, 2024 | Sciammas Maurice | 2,344 |
| Feb 13, 2024 | Moyer James C | 16K |
| Feb 6, 2024 | CHANG KUO WEI HERBERT | 348 |
| Feb 6, 2024 | Lee Victor K | 348 |
| Feb 6, 2024 | Moyer James C | 348 |
| Feb 6, 2024 | Zhou Jeff | 348 |
| Feb 6, 2024 | Elmiger Eugen J | 348 |
| Feb 6, 2024 | Wynne Eileen | 348 |
| Feb 6, 2024 | Martinez Carintia | 348 |
| Nov 16, 2023 | Moyer James C | 7,600 |
| Nov 14, 2023 | Xiao Deming | 6,782 |
Where the shares went, last 12 months
Every Form 4 movement decomposed: what flowed in (grants, vested equity, purchases) and what flowed out (tax withholding, plan sales, discretionary sales, gifts). Counted in shares, because grants carry no price.
The chart, in numbers
| Flow | Shares |
|---|---|
| Granted | 1.1M |
| Withheld for tax | 334K |
| Planned sales (10b5-1) | 222K |
| Discretionary sales | 399K |
| Gifts | 59K |
| Other out | 2,161 |
| Kept | 130K |
Skin in the game
Directly held shares as reported after each trade, indexed to 100 at the start of the window, up to five years back. Direct holdings only: trust and family-entity positions are per-entity in the filings and do not sum honestly, so this chart refuses to guess. The steps are the trades.
The chart, in numbers
| Insider | Start of the window | Latest reported | Indexed, start = 100 |
|---|---|---|---|
| Hsing Michael | 975K | 853K | 87.5 |
| Xiao Deming | 283K | 206K | 72.7 |
| Sciammas Maurice | 276K | 127K | 45.9 |
| Tseng Saria | 255K | 142K | 55.9 |
| BLEGEN THEODORE | 129K | 82K | 64.1 |
Who holds what
| Insider | Role | Shares held | Buys 12 m | Sales 12 m | 12 m | Last trade |
|---|---|---|---|---|---|---|
| Hsing Michael CEO Last trade May 18, 2026 | CEO | 898K | – | $314M | net selling over the year: 0 months buying, 3 months selling | May 18, 2026 |
| Xiao Deming EVP, Global Operations Last trade May 6, 2026 | Officer | 237K | – | $76M | net selling over the year: 0 months buying, 2 months selling | May 6, 2026 |
| Sciammas Maurice EVP, WW Sales & Marketing Last trade Aug 3, 2026 | Officer | 163K | – | $101M | net selling over the year: 0 months buying, 8 months selling | Aug 3, 2026 |
| Tseng Saria EVP & General Counsel Last trade May 27, 2026 | Officer | 144K | – | $164M | net selling over the year: 0 months buying, 7 months selling | May 27, 2026 |
| BLEGEN THEODORE EVP and CFO Last trade Feb 6, 2026 | CFO | 88K | – | $40M | net selling over the year: 0 months buying, 5 months selling | Feb 6, 2026 |
| Lee Victor K Last trade Feb 9, 2026 | Director | 28K | – | $2.0M | net selling over the year: 0 months buying, 3 months selling | Feb 9, 2026 |
| Elmiger Eugen J Last trade May 6, 2026 | Director | 17K | – | $19M | net selling over the year: 0 months buying, 1 month selling | May 6, 2026 |
| DEAN ROBERT W II Interim CFO Last trade Aug 24, 2026 | CFO | 7,094 | – | $234K | net selling over the year: 0 months buying, 2 months selling | Aug 24, 2026 |
| Zhou Jeff Last trade May 26, 2026 | Director | 3,800 | – | $3.3M | net selling over the year: 0 months buying, 1 month selling | May 26, 2026 |
| Martinez Carintia Last trade Sep 18, 2025 | Director | 1,067 | – | $1.3M | net selling over the year: 0 months buying, 1 month selling | Sep 18, 2025 |
| Wynne Eileen Last trade May 6, 2026 | Director | 1,007 | – | $530K | net selling over the year: 0 months buying, 1 month selling | May 6, 2026 |
| CHANG KUO WEI HERBERT Last trade Aug 24, 2026 | Director | 515 | – | $312K | net selling over the year: 0 months buying, 2 months selling | Aug 24, 2026 |
| Moyer James C Last trade Nov 16, 2023 | Director | 348 | – | – | Nov 16, 2023 |
Open-market trade log
the 60 most recent of 6,054| Date | Insider | Type | Shares | Price | Value | Since trade | Filed |
|---|---|---|---|---|---|---|---|
| Aug 24, 2026 | CHANG KUO WEI HERBERT (Director) 50 shares $1,281.57 +4.9% since trade filed Aug 25, 2026 | Discretionary sale | 50 | $1,281.57 | $64K | +4.9% | Aug 25, 2026 |
| Aug 24, 2026 | DEAN ROBERT W II (CFO) 32 shares $1,297.72 +3.6% since trade filed Aug 26, 2026 | Discretionary sale | 32 | $1,297.72 | $42K | +3.6% | Aug 26, 2026 |
| Aug 17, 2026 | DEAN ROBERT W II (CFO) 6 shares $1,413.64 −4.9% since trade filed Aug 19, 2026 | Discretionary sale | 6 | $1,413.64 | $8K | −4.9% | Aug 19, 2026 |
| Aug 11, 2026 | CHANG KUO WEI HERBERT (Director) 50 shares $1,420.00 −5.3% since trade filed Aug 13, 2026 | Discretionary sale | 50 | $1,420.00 | $71K | −5.3% | Aug 13, 2026 |
| Aug 5, 2026 | DEAN ROBERT W II (CFO) 105 shares $1,344.27 +0.0% since trade filed Aug 6, 2026 | Discretionary sale | 105 | $1,344.27 | $141K | +0.0% | Aug 6, 2026 |
| Aug 3, 2026 | Sciammas Maurice (Officer) 30 shares $1,343.94 +0.0% since trade filed Aug 5, 2026 | Planned sale (10b5-1) | 30 | $1,343.94 | $40K | +0.0% | Aug 5, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 50 shares $1,359.36 −1.1% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 50 | $1,359.36 | $68K | −1.1% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 50 shares $1,388.19 −3.2% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 50 | $1,388.19 | $69K | −3.2% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 110 shares $1,405.71 −4.4% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 110 | $1,405.71 | $155K | −4.4% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 117 shares $1,400.45 −4.0% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 117 | $1,400.45 | $164K | −4.0% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 213 shares $1,396.16 −3.7% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 213 | $1,396.16 | $297K | −3.7% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 240 shares $1,369.18 −1.8% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 240 | $1,369.18 | $329K | −1.8% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 274 shares $1,318.42 +2.0% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 274 | $1,318.42 | $361K | +2.0% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 409 shares $1,323.93 +1.5% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 409 | $1,323.93 | $541K | +1.5% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 410 shares $1,384.11 −2.9% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 410 | $1,384.11 | $567K | −2.9% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 418 shares $1,378.73 −2.5% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 418 | $1,378.73 | $576K | −2.5% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 464 shares $1,329.30 +1.1% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 464 | $1,329.30 | $617K | +1.1% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 472 shares $1,375.47 −2.3% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 472 | $1,375.47 | $649K | −2.3% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 527 shares $1,314.03 +2.3% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 527 | $1,314.03 | $692K | +2.3% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 776 shares $1,334.59 +0.7% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 776 | $1,334.59 | $1.0M | +0.7% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 1,460 shares $1,339.59 +0.4% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 1,460 | $1,339.59 | $2.0M | +0.4% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 1,506 shares $1,348.91 −0.3% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 1,506 | $1,348.91 | $2.0M | −0.3% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 1,864 shares $1,344.16 +0.0% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 1,864 | $1,344.16 | $2.5M | +0.0% | Jul 17, 2026 |
| Jul 15, 2026 | Sciammas Maurice (Officer) 5,640 shares $1,352.95 −0.6% since trade filed Jul 17, 2026 | Planned sale (10b5-1) | 5,640 | $1,352.95 | $7.6M | −0.6% | Jul 17, 2026 |
| Jul 1, 2026 | Sciammas Maurice (Officer) 30 shares $1,351.61 −0.5% since trade filed Jul 6, 2026 | Planned sale (10b5-1) | 30 | $1,351.61 | $41K | −0.5% | Jul 6, 2026 |
| Jun 1, 2026 | Sciammas Maurice (Officer) 30 shares $1,533.95 −12.4% since trade filed Jun 3, 2026 | Planned sale (10b5-1) | 30 | $1,533.95 | $46K | −12.4% | Jun 3, 2026 |
| May 27, 2026 | Tseng Saria (Officer) 7,565 shares $1,700.00 −20.9% since trade filed May 29, 2026 | Discretionary sale | 7,565 | $1,700.00 | $13M | −20.9% | May 29, 2026 |
| May 26, 2026 | DEAN ROBERT W II (CFO) 22 shares $1,649.56 −18.5% since trade filed May 28, 2026 | Discretionary sale | 22 | $1,649.56 | $36K | −18.5% | May 28, 2026 |
| May 26, 2026 | Zhou Jeff (Director) 486 shares $1,680.00 −20.0% since trade filed May 27, 2026 | Discretionary sale | 486 | $1,680.00 | $816K | −20.0% | May 27, 2026 |
| May 22, 2026 | Tseng Saria (Officer) 5,000 shares $1,586.43 −15.3% since trade filed May 27, 2026 | Discretionary sale | 5,000 | $1,586.43 | $7.9M | −15.3% | May 27, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 130 shares $1,521.43 −11.6% since trade filed May 20, 2026 | Discretionary sale | 130 | $1,521.43 | $198K | −11.6% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 352 shares $1,518.15 −11.5% since trade filed May 20, 2026 | Discretionary sale | 352 | $1,518.15 | $534K | −11.5% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 551 shares $1,513.11 −11.2% since trade filed May 20, 2026 | Discretionary sale | 551 | $1,513.11 | $834K | −11.2% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 608 shares $1,499.46 −10.4% since trade filed May 20, 2026 | Discretionary sale | 608 | $1,499.46 | $912K | −10.4% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 862 shares $1,491.48 −9.9% since trade filed May 20, 2026 | Discretionary sale | 862 | $1,491.48 | $1.3M | −9.9% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 2,929 shares $1,503.05 −10.6% since trade filed May 20, 2026 | Discretionary sale | 2,929 | $1,503.05 | $4.4M | −10.6% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 3,424 shares $1,462.61 −8.1% since trade filed May 20, 2026 | Discretionary sale | 3,424 | $1,462.61 | $5.0M | −8.1% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 3,769 shares $1,507.70 −10.8% since trade filed May 20, 2026 | Discretionary sale | 3,769 | $1,507.70 | $5.7M | −10.8% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 4,082 shares $1,476.96 −9.0% since trade filed May 20, 2026 | Discretionary sale | 4,082 | $1,476.96 | $6.0M | −9.0% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 5,049 shares $1,472.84 −8.7% since trade filed May 20, 2026 | Discretionary sale | 5,049 | $1,472.84 | $7.4M | −8.7% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 5,737 shares $1,482.51 −9.3% since trade filed May 20, 2026 | Discretionary sale | 5,737 | $1,482.51 | $8.5M | −9.3% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 5,819 shares $1,467.62 −8.4% since trade filed May 20, 2026 | Discretionary sale | 5,819 | $1,467.62 | $8.5M | −8.4% | May 20, 2026 |
| May 18, 2026 | Hsing Michael (CEO) 6,688 shares $1,486.76 −9.6% since trade filed May 20, 2026 | Discretionary sale | 6,688 | $1,486.76 | $9.9M | −9.6% | May 20, 2026 |
| May 18, 2026 | DEAN ROBERT W II (CFO) 4 shares $1,563.28 −14.0% since trade filed May 20, 2026 | Discretionary sale | 4 | $1,563.28 | $6K | −14.0% | May 20, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 50 shares $1,585.51 −15.2% since trade filed May 19, 2026 | Planned sale (10b5-1) | 50 | $1,585.51 | $79K | −15.2% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 447 shares $1,582.21 −15.0% since trade filed May 19, 2026 | Planned sale (10b5-1) | 447 | $1,582.21 | $707K | −15.0% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 703 shares $1,577.75 −14.8% since trade filed May 19, 2026 | Planned sale (10b5-1) | 703 | $1,577.75 | $1.1M | −14.8% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 1,312 shares $1,571.49 −14.5% since trade filed May 19, 2026 | Planned sale (10b5-1) | 1,312 | $1,571.49 | $2.1M | −14.5% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 1,717 shares $1,557.48 −13.7% since trade filed May 19, 2026 | Planned sale (10b5-1) | 1,717 | $1,557.48 | $2.7M | −13.7% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 2,010 shares $1,562.01 −13.9% since trade filed May 19, 2026 | Planned sale (10b5-1) | 2,010 | $1,562.01 | $3.1M | −13.9% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 2,020 shares $1,567.15 −14.2% since trade filed May 19, 2026 | Planned sale (10b5-1) | 2,020 | $1,567.15 | $3.2M | −14.2% | May 19, 2026 |
| May 15, 2026 | Sciammas Maurice (Officer) 3,741 shares $1,550.36 −13.3% since trade filed May 19, 2026 | Planned sale (10b5-1) | 3,741 | $1,550.36 | $5.8M | −13.3% | May 19, 2026 |
| May 6, 2026 | Xiao Deming (Officer) 907 shares $1,661.38 −19.1% since trade filed May 8, 2026 | Discretionary sale | 907 | $1,661.38 | $1.5M | −19.1% | May 8, 2026 |
| May 6, 2026 | Xiao Deming (Officer) 3,329 shares $1,648.38 −18.5% since trade filed May 8, 2026 | Discretionary sale | 3,329 | $1,648.38 | $5.5M | −18.5% | May 8, 2026 |
| May 6, 2026 | Xiao Deming (Officer) 12K shares $1,657.93 −18.9% since trade filed May 8, 2026 | Discretionary sale | 12K | $1,657.93 | $19M | −18.9% | May 8, 2026 |
| May 6, 2026 | Xiao Deming (Officer) 14K shares $1,652.80 −18.7% since trade filed May 8, 2026 | Discretionary sale | 14K | $1,652.80 | $23M | −18.7% | May 8, 2026 |
| May 6, 2026 | Zhou Jeff (Director) 500 shares $1,650.00 −18.5% since trade filed May 6, 2026 | Discretionary sale | 500 | $1,650.00 | $825K | −18.5% | May 6, 2026 |
| May 6, 2026 | Elmiger Eugen J (Director) 320 shares $1,559.88 −13.8% since trade filed May 8, 2026 | Discretionary sale | 320 | $1,559.88 | $499K | −13.8% | May 8, 2026 |
| May 6, 2026 | Elmiger Eugen J (Director) 514 shares $1,600.14 −16.0% since trade filed May 8, 2026 | Discretionary sale | 514 | $1,600.14 | $822K | −16.0% | May 8, 2026 |
| May 6, 2026 | Elmiger Eugen J (Director) 814 shares $1,566.36 −14.2% since trade filed May 8, 2026 | Discretionary sale | 814 | $1,566.36 | $1.3M | −14.2% | May 8, 2026 |
“Since trade” compares with the latest insider-implied price, not a market quote: these pages are built from filings alone. A role here is the one on that day's Form 4, so somebody promoted since appears under both titles.
Filing hygiene
235 Forms 4, 3 years
1 filed late
0 amendments
1.6 avg. days to file
How to read this
A Form 4 transaction code decides everything. P is an open-market purchase and S an open-market sale; those two are the only codes where an insider chose to trade. A is a grant, M an option exercise or vesting, F shares withheld to cover tax, G a gift. Most “insiders dumped billions” headlines are code F and M mechanics.
Sales flagged 10b5-1 run on a plan the insider adopted in advance; since 2023 every Form 4 carries that flag. Buys have historically predicted returns, sales mostly have not, and this page states filings, not advice.