undamentalytics Newsletter

Chang Kuo Wei Herbert: insider trades

Director at Monolithic Power Systems, Inc. No open-market purchases and 63 sales not made under a pre-set plan, reported from November 22, 2010 to August 25, 2026.

What happened after Chang Kuo Wei Herbert’s sales?

After their sales, the shares moved +24.4% against the index over 12 months on average (a negative figure means selling was the right call); 17% trailed it.

With 296 insiders tested, some will look skilled or unskilled by chance alone: when we replaced each insider’s stocks with random companies bought on the same days, about 5.7 cleared the bar ahead and 23.3 behind. One record on its own proves little.

Trade by trade

Chang Kuo Wei Herbert: trades against the S&P 500 afterwards
MeasuredTrades countedAverage vs S&P 500MedianWent the right wayYearst-statisticp-valueEvidence
Purchases, 3 months after the report 0 — — — — — — Not enough years
Purchases, 6 months after the report 0 — — — — — — Not enough years
Purchases, 12 months after the report 0 — — — — — — Not enough years
Purchases, 12 months after the trade 0 — — — — — — Not enough years
Sales, 3 months after the report 61 +0.3% +0.6% 49% 10 −0.04 0.97 No reliable evidence
Sales, 12 months after the report 59 +24.4% +24.4% 17% 10 1.78 0.11 No reliable evidence
Sales, 12 months after the trade 59 +25.8% +24.6% 17% 10 1.80 0.11 No reliable evidence

“Average vs S&P 500” is the stock’s return including dividends minus the index’s over the same dates, from the close on the first trading day after the report, or from the close on the trade date. Only windows that have finished are counted. For sales, a negative figure means the stock lagged after it was sold, so selling was the right call (green). “Went the right way” is the share of purchases that beat the index, or of sales that trailed it. The t-statistic uses one average per year of reports, because one person’s trades bunch into the same stock and weeks, and needs trades in at least four different years; the p-value comes from the t distribution with that number of years (with four years, a t of 2 has p = 0.14). “Some evidence” means p under 5%, “strong evidence” p under 1% over at least six years.

Companies traded

CompanyTitle on the latest filingPurchasesSalesFirst reportLatest report
Monolithic Power Systems, Inc. MPWR —063November 22, 2010August 25, 2026

Trades and what followed

Moves are against the S&P 500; green means the trade went the insider’s way.

ReportedTradedCompanyTradeValue3 months after report12 months after report12 months after trade
August 25, 2026August 24, 2026 MPWR Sale $64,078 not yetnot yetnot yet
August 13, 2026August 11, 2026 MPWR Sale $71,000 not yetnot yetnot yet
November 25, 2025November 25, 2025 MPWR Sale $89,697 +22.5%not yetnot yet
November 24, 2025November 21, 2025 MPWR Sale $87,397 +24.1%not yetnot yet
May 13, 2025May 13, 2025 MPWR Sale $36,900 +5.8%+85.5%+91.5%
May 12, 2025May 12, 2025 MPWR Sale $69,800 +6.8%+91.5%+105.7%
May 9, 2025May 8, 2025 MPWR Sale $65,000 +8.2%+105.7%+129.2%
August 15, 2024August 15, 2024 MPWR Sale $178,688 −44.2%−25.5%−24.6%
May 22, 2024May 20, 2024 MPWR Sale $150,000 +18.4%−21.7%−21.8%
May 15, 2024May 15, 2024 MPWR Sale $147,000 +20.6%−16.7%−18.2%
February 29, 2024February 29, 2024 MPWR Sale $176,585 −4.1%−32.3%−32.7%
February 23, 2024February 22, 2024 MPWR Sale $187,500 −0.8%−32.5%−30.1%
November 15, 2023November 14, 2023 MPWR Sale $209,456 +22.1%−22.2%−25.6%
November 13, 2023November 13, 2023 MPWR Sale $51,000 +25.0%−25.6%−18.1%
August 29, 2023August 29, 2023 MPWR Sale $250,000 +6.3%+56.0%+56.7%
February 26, 2021February 26, 2021 MPWR Sale $111,000 −19.8%+5.0%+7.3%
November 5, 2020November 4, 2020 MPWR Sale $978,990 −5.6%+18.6%+22.4%
September 1, 2020August 28, 2020 MPWR Sale $348,400 +10.7%+48.7%+57.0%
August 14, 2020August 12, 2020 MPWR Sale $111,800 +2.9%+28.6%+32.3%
August 10, 2020August 6, 2020 MPWR Sale $196,300 +10.5%+35.8%+30.2%
August 5, 2020August 3, 2020 MPWR Sale $349,620 +15.9%+30.2%+35.0%
May 12, 2020May 8, 2020 MPWR Sale $637,408 +20.1%+6.4%+8.2%
May 7, 2020May 5, 2020 MPWR Sale $198,000 +17.3%+8.2%+25.2%
February 14, 2020February 13, 2020 MPWR Sale $192,000 +22.7%+88.2%+84.7%
February 12, 2020February 11, 2020 MPWR Sale $187,720 +20.3%+84.7%+80.4%
February 27, 2014February 26, 2014 MPWR Sale $261,579 +5.7%+36.6%+30.7%
February 25, 2014February 24, 2014 MPWR Sale $177,900 +4.4%+30.7%+32.2%
November 29, 2013November 27, 2013 MPWR Sale $355,841 +8.4%+30.9%+28.2%
November 13, 2013November 11, 2013 MPWR Sale $652,600 +4.2%+24.4%+22.1%
November 8, 2013November 6, 2013 MPWR Sale $128,000 +4.0%+22.1%+24.4%
August 28, 2013August 28, 2013 MPWR Sale $174,300 −0.3%+33.9%+37.8%
August 26, 2013August 26, 2013 MPWR Sale $116,120 +1.7%+39.2%+40.3%
August 19, 2013August 15, 2013 MPWR Sale $234,400 +3.6%+36.9%+33.9%
August 14, 2013August 12, 2013 MPWR Sale $219,490 +7.9%+33.9%+33.2%
May 31, 2013May 28, 2013 MPWR Sale $677,975 +23.5%+37.2%+44.0%
March 1, 2013February 27, 2013 MPWR Sale $255,665 −5.9%+27.5%+22.4%
August 30, 2012August 29, 2012 MPWR Sale $44,020 −1.2%+28.8%+26.0%
August 29, 2012August 27, 2012 MPWR Sale $216,695 −1.5%+29.6%+21.9%
August 24, 2012August 23, 2012 MPWR Sale $256,870 −10.2%+21.9%+17.0%
August 23, 2012August 21, 2012 MPWR Sale $331,480 −10.0%+16.1%+18.3%
August 17, 2012August 16, 2012 MPWR Sale $385,740 −9.8%+18.6%+19.7%
August 15, 2012August 14, 2012 MPWR Sale $24,400 −10.1%+19.7%+23.9%
August 10, 2012August 9, 2012 MPWR Sale $421,600 −6.4%+24.2%+22.0%
February 29, 2012February 29, 2012 MPWR Sale $284,850 +4.7%+23.0%+22.7%
February 27, 2012February 24, 2012 MPWR Sale $187,900 +0.8%+20.6%+22.3%
February 24, 2012February 22, 2012 MPWR Sale $364,064 −2.2%+18.6%+31.6%
February 17, 2012February 17, 2012 MPWR Sale $18,738 +11.3%+33.3%+28.7%
August 30, 2011August 30, 2011 MPWR Sale $125,400 −7.5%+52.7%+52.6%
August 29, 2011August 29, 2011 MPWR Sale $62,800 −10.9%+52.6%+54.4%
August 24, 2011August 23, 2011 MPWR Sale $60,850 −9.6%+61.1%+52.6%
August 17, 2011August 17, 2011 MPWR Sale $14,312 +0.6%+62.7%+52.9%
August 11, 2011August 11, 2011 MPWR Sale $62,650 −8.0%+46.2%+46.9%
May 31, 2011May 31, 2011 MPWR Sale $319,621 −16.0%+11.1%+8.4%
May 31, 2011May 27, 2011 MPWR Sale $338,000 −16.0%+11.1%+9.3%
May 20, 2011May 6, 2011 MPWR Sale $123,975 −14.3%+13.6%+23.5%
May 19, 2011May 19, 2011 MPWR Sale $242,283 −15.7%+14.6%+16.2%
May 18, 2011May 18, 2011 MPWR Sale $208,125 −16.3%+16.2%+24.6%
May 13, 2011May 13, 2011 MPWR Sale $546,975 −13.9%+25.0%+26.6%
May 13, 2011May 12, 2011 MPWR Sale $248,400 −13.9%+25.0%+23.6%
May 4, 2011May 3, 2011 MPWR Sale $253,992 −9.7%+23.2%+25.1%
December 1, 2010November 30, 2010 MPWR Sale $161,800 −19.9%−31.3%−33.5%
November 30, 2010November 29, 2010 MPWR Sale $165,100 −18.1%−32.4%−33.1%
November 22, 2010November 19, 2010 MPWR Sale $321,000 −20.3%−33.4%−27.9%

Open-market purchases and sales of at least $10,000 in companies we cover, from SEC Form 4 filings; sales made under a pre-set Rule 10b5-1 plan are not shown. “Not yet” means the window has not finished or the share price was under $5 at entry. These are the shares’ moves after each trade: they say nothing about why Chang Kuo Wei Herbert traded and do not suggest the use of non-public information. How every insider compares · the insider trading backtest.