This is the public record of open-market stock transactions Michael Hsing has reported to the SEC on Form 4 as CEO of MONOLITHIC POWER SYSTEMS INC (MPWR). Every figure below is the reported share count multiplied by the reported price, so the dollar amounts are exact disclosed values rather than estimates. It is a record of what has been filed, not a portfolio or a recommendation, and insider selling in particular is routine and rarely a signal on its own.
Most of Michael Hsing's sales were pre-scheduled or tax-related rather than discretionary, which further weakens any read of them as a market call.
All 9 disclosed transactions, newest filing first.
How many shares has Michael Hsing bought and sold?
Michael Hsing has disclosed 9 Form 4 transactions in the record we track, from Aug 15, 2025 to Sep 28, 2026: 9 sales worth $371,558,595 and no open-market purchases. Each figure is the reported share count multiplied by the reported price, so these are exact disclosed amounts, not estimates.
Is Michael Hsing selling a bearish signal?
Not on its own. Insiders sell for many reasons that have nothing to do with a view on the stock — diversification, taxes, estate planning, or a pre-scheduled plan set up months earlier. Of the 9 sales on this record, 4 were made under a Rule 10b5-1 plan and 1 were automatic tax withholding on vesting shares, leaving 4 that were the insider's own discretionary decision (worth $150,143,820). Buying is the cleaner signal, because there is only one reason to buy. This page is a record, not a recommendation.
What is Michael Hsing's role?
Michael Hsing files as CEO of MONOLITHIC POWER SYSTEMS INC (MPWR). That role is taken from the Form 4 filings themselves. A Form 4 is filed with the SEC within two business days of an insider buying or selling their own company's stock.
What was Michael Hsing's largest single transaction?
The largest single transaction on record is a sell of 54,923 shares of MPWR at $1171.16, worth $64,323,824, filed Feb 10, 2026.
How current is this record?
The most recent Form 4 here was filed Sep 30, 2026. Insiders have two business days to file after a trade, so this is close to real time, but it is a record of what has been disclosed, not a statement of what Michael Hsing currently holds. Amounts are open-market and plan transactions reported on Form 4; grants and option exercises are not counted as buys.
Source: Form 4 filings submitted to the SEC, the same public documents behind our insider trading tracker. Figures are open-market and plan transactions only; grants and option exercises are not counted as buys. A disclosure is not evidence of a market view, and none of this is investment advice. See the full MPWR stock page for price, filings and coverage.