Wednesday, October 28, 2026
Data from SEC filings, checked daily
Public filings, plainly told
WallStPal · PDF guide
MPWR Insider Trading and Fund Holdings (MONOLITHIC POWER SYSTEMS, INC.) · https://wallstpal.com/stock/mpwr/ · saved 2026-10-28

About this page

Insider trades reported on SEC Form 4: when the people who run a company buy or sell its shares with their own money.

How to read it

Form 4
The form a company insider (officer, director or owner of more than 10%) must file with the SEC within two business days of buying or selling the company's shares.
Buy (P) and Sell (S)
Open-market purchases and sales. Gifts, option exercises and automatic tax withholding are left out because they say little about what the insider thinks.
Value
Shares times price, as reported on the filing.
10b5-1
A trade made under a plan set up in advance. Planned sales are common and usually say less than an unplanned purchase.
Late filing
A Form 4 filed more than two business days after the trade.
Vs. S&P 500
How the stock did after the trade minus how the overall market did in the same weeks.

A real example

In January 2016, when bank stocks were falling, JPMorgan Chase CEO Jamie Dimon bought 500,000 JPMorgan shares with his own money, worth about $26 million. His Form 4 made the purchase public within days, and investors read it as a strong sign of confidence.

Explain it like I'm 13

If the coach of a team bets his own allowance that his team will win, that tells you something. A Form 4 is the note a company boss must hand in whenever he buys or sells his own company's shares, so everyone can see it.

Data from public SEC filings and congressional reports. Information, not investment advice. Check every number against the filing linked on the page.

Summarize with AIChatGPTClaudePerplexityGoogle AIGrokCopilot
StockCIK 1280452

MONOLITHIC POWER SYSTEMS, INC. (MPWR): Insider Trades and Fund Holdings

In the past 12 months, MONOLITHIC POWER SYSTEMS, INC. insiders reported no open-market purchases and 9 sales worth $61.0M; 4 of the sales were reported as made under a 10b5-1 trading plan.

0Insider buys, 12 months
$0Bought by insiders, 12 months
$61.0MSold by insiders, 12 months
2Tracked funds holding

Timeline: news and trades

Company filings (8-K), insider trades, notices of planned sales (Form 144), Congress trades and fund moves in the past year, newest first.

  1. Sep 28, 2026Insider saleCEO Michael Hsing sold $40.3 million under a 10b5-1 plan
  2. Sep 28, 2026Planned saleMICHAEL HSING (officer, director) filed notice to sell about $40.3 million around Sep 28, 2026
  3. Aug 24, 2026Insider saleCFO Robert W. Dean II sold $41,527
  4. Aug 24, 2026Insider saleDirector Kuo Wei Herbert Chang sold $64,079
  5. Aug 24, 2026Planned saleDEAN ROBERT W II (officer) filed notice to sell about $41,527 around Aug 24, 2026
  6. Aug 17, 2026Insider saleCFO Robert W. Dean II sold $8,482
  7. Aug 17, 2026Planned saleDEAN ROBERT W II (officer) filed notice to sell about $8,128 around Aug 17, 2026
  8. Aug 11, 2026Insider saleDirector Kuo Wei Herbert Chang sold $71,000
  9. Aug 11, 2026Planned saleKuo Wei Chang (director) filed notice to sell about $142,000 around Aug 11, 2026
  10. Aug 5, 2026Insider saleCFO Robert W. Dean II sold $141,148 (6 days after: quarterly or annual results)
  11. Aug 5, 2026Planned saleROBERT DEAN (officer) filed notice to sell about $141,148 around Aug 5, 2026
  12. Aug 3, 2026Insider saleEVP Maurice Sciammas sold $40,318 under a 10b5-1 plan (4 days after: quarterly or annual results)
  13. Jul 30, 2026NewsCompany reported: Quarterly or annual results
  14. Jul 15, 2026Insider saleEVP Maurice Sciammas sold $20.2 million under a 10b5-1 plan
  15. Jul 1, 2026Insider saleEVP Maurice Sciammas sold $40,548 under a 10b5-1 plan
  16. Jun 30, 2026FundBridgewater Associates cut 74% in Q2 2026 (13F filed Aug 14, 2026)
  17. Jun 30, 2026FundRenaissance Technologies opened a position in Q2 2026 (13F filed Aug 13, 2026)
  18. Jun 5, 2026CongressRep. Byron Donalds partial sell $1K–$15K (spouse)
  19. Jun 5, 2026CongressRep. Byron Donalds partial sell $1K–$15K

Recent insider trades

Open-market purchases (code P) and sales (code S) from Form 4. Grants, option exercises and gifts are not shown. Latest filing: Sep 30, 2026.

Recent MPWR insider trades
FiledTradedInsiderRoleTypeSharesPrice ($)ValueHoldingFiling
Sep 30Sep 28Michael HsingCEOCEO▼ SELL10b5-130,0001344.97$40.3M−3.5%Form 4 ↗
Aug 26Aug 24Robert W. Dean IICFOCFO▼ SELL321297.72$42K−0.4%Form 4 ↗
Aug 25Aug 24Kuo Wei Herbert ChangDirectorDirector▼ SELL501281.58$64K−8.8%Form 4 ↗
Aug 19Aug 17Robert W. Dean IICFOCFO▼ SELL61413.67$8K−0.1%Form 4 ↗
Aug 13Aug 11Kuo Wei Herbert ChangDirectorDirector▼ SELL501420.00$71K−8.1%Form 4 ↗
Aug 6Aug 5Robert W. Dean IICFOCFO▼ SELL1051344.27$141K−1.5%Form 4 ↗
Aug 5Aug 3Maurice SciammasEVPEVP (ind.)▼ SELL10b5-1301343.93$40K−2.6%Form 4 ↗
Jul 17Jul 15Maurice SciammasEVPEVP▼ SELL10b5-115,0001349.73$20.2M−8.9%Form 4 ↗
Jul 6Jul 1Maurice SciammasEVPEVP (ind.)▼ SELL10b5-1301351.60$41K−2.5%Form 4 ↗
Source: SEC Form 4 filings, retrieved Oct 28, 2026. How we read filings

Insiders who traded in the past year

InsiderRoleBuysBoughtSellsSoldLatest
Michael HsingCEO0$01$40.3MSep 30, 2026
Robert W. Dean IICFO0$03$191KAug 26, 2026
Kuo Wei Herbert ChangDirector0$02$135KAug 25, 2026
Maurice SciammasEVP0$03$20.3MAug 5, 2026

Trades by members of Congress

Reported under the STOCK Act. Amounts are ranges from the form. All Congress trades →

Congress trades in MPWR
FiledMemberTypeOwnerAmountTradedDays to reportReport
Jul 15▼ PARTIAL SELLSpouse$1K–$15KJun 540PDF ↗
Jul 15▼ PARTIAL SELLMember$1K–$15KJun 540PDF ↗
Nov 19▲ BUYChild$1K–$15KOct 2030PDF ↗

Buybacks and executive pay

MONOLITHIC POWER SYSTEMS, INC. spent $6.6 million buying back its own shares in 2025.

YearCEO pay reportedCEO pay "actually paid"Value of $100 invested
2025$19.9M$250.2Mn/a
2024$19.0M$21.9Mn/a
2023$14.6M$138.3Mn/a

From the company's XBRL data filed with the SEC. "Actually paid" is the SEC's pay-versus-performance measure, which counts changes in the value of stock awards. "Value of $100 invested" is the company's cumulative shareholder return as reported, usually measured from five years earlier. See all buybacks and CEO pay across companies.

Filing quality

A All 9 insider trades reported on time. How it is graded

Tracked funds that report MPWR

From each fund's latest 13F. Holdings are as of quarter end and are filed up to 45 days later.

FundQuarterSharesValue% of portfolioChange
Renaissance TechnologiesQ2 202663,066$87.2M0.12%▲ New
Bridgewater AssociatesQ2 20263,096$4.28M0.02%▼ −74.1%
Source: SEC Form 13F-HR filings, retrieved Oct 28, 2026. How we read filings

Reading these numbers

Insiders sell for many reasons: taxes, diversification, a house. Purchases with their own money are rarer and are usually read as more informative. A Form 4 is due within two business days of the trade. How to read a Form 4 →