undamentalytics Newsletter

Tseng Saria: insider trades

Officer at Monolithic Power Systems, Inc. No open-market purchases and 125 sales not made under a pre-set plan, reported from May 12, 2010 to May 29, 2026.

What happened after Tseng Saria’s sales?

After their sales, the shares moved +24.8% against the index over 12 months on average (a negative figure means selling was the right call); 18% 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

Tseng Saria: 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 125 +5.4% +6.0% 36% 17 2.56 0.021 Some evidence: seller wrong
Sales, 12 months after the report 120 +24.8% +24.3% 18% 16 3.68 0.002 Strong evidence: seller wrong
Sales, 12 months after the trade 120 +24.1% +25.0% 15% 16 3.56 0.003 Strong evidence: seller wrong

“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 EVP & General Counsel0125May 12, 2010May 29, 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
May 29, 2026May 27, 2026 MPWR Sale $12,860,500 −19.1%not yetnot yet
May 27, 2026May 22, 2026 MPWR Sale $7,932,150 −22.0%not yetnot yet
February 10, 2026February 6, 2026 MPWR Sale $26,790,285 +30.6%not yetnot yet
November 28, 2025November 26, 2025 MPWR Sale $18,529,316 +17.6%not yetnot yet
November 28, 2025November 25, 2025 MPWR Sale $18,083,638 +17.6%not yetnot yet
February 12, 2025February 10, 2025 MPWR Sale $475,437 +4.6%+55.7%+55.3%
November 13, 2024November 8, 2024 MPWR Sale $662,611 +16.7%+37.3%+11.3%
August 12, 2024August 8, 2024 MPWR Sale $668,637 −36.1%−24.2%−22.1%
July 24, 2024July 22, 2024 MPWR Sale $2,665,214 +4.3%−27.0%−32.0%
May 9, 2024May 8, 2024 MPWR Sale $599,627 +14.7%−8.9%−14.0%
February 9, 2024February 8, 2024 MPWR Sale $584,120 −7.8%−26.7%−27.5%
February 7, 2024February 5, 2024 MPWR Sale $629,462 −8.5%−27.5%−21.7%
January 8, 2024January 4, 2024 MPWR Sale $14,761,606 +3.6%−23.8%−17.8%
November 9, 2023November 8, 2023 MPWR Sale $421,245 +28.8%−8.8%+16.8%
November 7, 2023November 6, 2023 MPWR Sale $484,047 +37.8%+16.8%+22.6%
October 4, 2023October 2, 2023 MPWR Sale $1,972,982 +16.6%+71.7%+66.4%
August 10, 2023August 8, 2023 MPWR Sale $463,456 −1.5%+50.7%+40.5%
August 7, 2023August 4, 2023 MPWR Sale $520,202 −4.0%+40.5%+29.7%
July 25, 2023July 21, 2023 MPWR Sale $5,136,621 −14.1%+35.3%+35.6%
July 5, 2023July 3, 2023 MPWR Sale $2,315,186 −7.9%+38.7%+29.8%
May 10, 2023May 9, 2023 MPWR Sale $351,207 +17.7%+49.5%+49.3%
May 5, 2023May 4, 2023 MPWR Sale $455,464 +17.6%+44.6%+31.6%
May 4, 2023May 3, 2023 MPWR Sale $1,604,810 +22.3%+44.9%+25.8%
April 6, 2023April 3, 2023 MPWR Sale $2,127,636 +2.8%+10.1%+4.8%
February 13, 2023February 13, 2023 MPWR Sale $806,896 −22.3%+18.7%+27.2%
February 10, 2023February 8, 2023 MPWR Sale $3,200,802 −18.0%+27.2%+39.8%
February 8, 2023February 6, 2023 MPWR Sale $323,094 −23.4%+19.2%+21.3%
January 5, 2023January 3, 2023 MPWR Sale $1,906,939 +27.3%+38.9%+43.2%
November 16, 2022November 14, 2022 MPWR Sale $653,451 +26.7%+30.8%+26.7%
November 7, 2022November 4, 2022 MPWR Sale $337,788 +36.6%+21.1%+23.3%
October 4, 2022October 3, 2022 MPWR Sale $1,604,043 −14.1%+3.8%+4.6%
August 12, 2022August 12, 2022 MPWR Sale $858,876 −19.9%−11.4%−6.3%
August 8, 2022August 4, 2022 MPWR Sale $514,032 −23.5%−7.9%−7.7%
July 6, 2022July 1, 2022 MPWR Sale $1,632,534 +6.3%+24.4%+26.4%
May 16, 2022May 12, 2022 MPWR Sale $651,620 +12.7%−6.2%0.0%
May 5, 2022May 4, 2022 MPWR Sale $446,816 +19.8%−10.6%−11.3%
April 5, 2022April 1, 2022 MPWR Sale $2,065,157 +4.5%+21.0%+13.3%
February 16, 2022February 14, 2022 MPWR Sale $714,425 +1.0%+12.3%+27.4%
February 9, 2022February 7, 2022 MPWR Sale $3,633,781 +7.9%+30.7%+24.2%
January 5, 2022January 3, 2022 MPWR Sale $2,113,195 −2.4%−1.3%−8.8%
November 16, 2021November 12, 2021 MPWR Sale $899,308 −11.6%−18.3%−16.3%
October 5, 2021October 1, 2021 MPWR Sale $2,061,773 −9.3%−1.9%−7.2%
August 16, 2021August 12, 2021 MPWR Sale $754,672 +18.9%+18.2%+17.5%
August 11, 2021August 9, 2021 MPWR Sale $942,573 +11.9%+17.5%+17.4%
July 6, 2021July 1, 2021 MPWR Sale $1,594,787 +24.7%+12.4%+9.3%
May 14, 2021May 12, 2021 MPWR Sale $542,879 +39.1%+36.7%+28.9%
May 12, 2021May 10, 2021 MPWR Sale $716,796 +42.3%+30.6%+30.5%
April 2, 2021April 1, 2021 MPWR Sale $1,570,378 −7.4%+10.4%+18.7%
February 19, 2021February 17, 2021 MPWR Sale $8,321,792 −20.3%+9.7%+11.6%
February 9, 2021February 5, 2021 MPWR Sale $6,419,436 −22.2%−5.1%−5.3%
January 5, 2021January 4, 2021 MPWR Sale $1,585,359 −4.0%+2.1%+5.2%
November 10, 2020November 9, 2020 MPWR Sale $1,481,118 +11.2%+43.9%+42.1%
October 2, 2020October 1, 2020 MPWR Sale $1,207,552 +21.6%+37.9%+42.7%
August 12, 2020August 10, 2020 MPWR Sale $1,210,104 +7.6%+33.3%+35.7%
July 6, 2020July 1, 2020 MPWR Sale $1,012,364 +7.3%+15.0%+17.5%
May 12, 2020May 8, 2020 MPWR Sale $952,579 +20.1%+6.4%+8.2%
April 3, 2020April 1, 2020 MPWR Sale $712,100 +24.9%+65.1%+66.8%
February 12, 2020February 10, 2020 MPWR Sale $421,350 +20.3%+84.7%+88.8%
February 6, 2020February 6, 2020 MPWR Sale $3,372,731 +29.1%+86.6%+81.1%
February 3, 2020February 3, 2020 MPWR Sale $504,977 +20.7%+83.9%+95.7%
January 9, 2020January 7, 2020 MPWR Sale $5,991,112 +12.4%+105.4%+86.9%
November 12, 2019November 8, 2019 MPWR Sale $387,817 +9.8%+79.2%+76.8%
November 5, 2019November 4, 2019 MPWR Sale $470,589 +4.1%+108.5%+85.6%
October 2, 2019October 1, 2019 MPWR Sale $669,901 +5.2%+64.0%+67.6%
August 9, 2019August 8, 2019 MPWR Sale $366,574 +6.1%+69.9%+68.5%
August 6, 2019August 5, 2019 MPWR Sale $431,080 +4.3%+76.6%+77.1%
July 3, 2019July 1, 2019 MPWR Sale $600,806 +13.2%+70.0%+66.2%
May 10, 2019May 8, 2019 MPWR Sale $340,934 +12.2%+63.3%+47.5%
May 7, 2019May 3, 2019 MPWR Sale $454,277 +6.3%+47.5%+33.9%
April 2, 2019April 1, 2019 MPWR Sale $596,673 −10.4%+20.3%+28.6%
February 13, 2019February 12, 2019 MPWR Sale $2,834,538 −10.4%+16.7%+20.6%
February 5, 2019February 4, 2019 MPWR Sale $469,505 −3.9%+11.5%+17.2%
November 6, 2018November 5, 2018 MPWR Sale $586,617 +7.4%+20.7%+17.6%
August 7, 2018August 3, 2018 MPWR Sale $641,466 −9.0%+2.2%+4.7%
May 7, 2018May 3, 2018 MPWR Sale $688,350 +6.8%+1.8%+5.0%
February 13, 2018February 12, 2018 MPWR Sale $3,191,280 +12.0%+18.9%+17.8%
February 5, 2018February 5, 2018 MPWR Sale $461,889 +9.5%+13.8%+19.1%
November 7, 2017November 6, 2017 MPWR Sale $689,997 −11.9%−4.4%−7.6%
August 7, 2017August 4, 2017 MPWR Sale $571,487 +16.6%+21.9%+19.1%
May 8, 2017May 4, 2017 MPWR Sale $517,104 +5.8%+21.0%+21.1%
February 13, 2017February 10, 2017 MPWR Sale $1,625,167 +12.4%+16.2%+8.5%
February 8, 2017February 6, 2017 MPWR Sale $416,805 +3.3%+9.0%+10.0%
November 8, 2016November 4, 2016 MPWR Sale $491,568 +3.5%+30.5%+37.2%
August 8, 2016August 4, 2016 MPWR Sale $459,200 +8.7%+24.2%+25.1%
May 25, 2016May 23, 2016 MPWR Sale $365,950 +6.8%+28.1%+27.5%
May 6, 2016May 4, 2016 MPWR Sale $391,101 +11.7%+34.4%+31.7%
February 9, 2016February 5, 2016 MPWR Sale $311,369 −1.4%+32.2%+24.8%
February 4, 2016February 4, 2016 MPWR Sale $1,277,762 −5.5%+24.8%+32.4%
November 10, 2015November 6, 2015 MPWR Sale $288,027 −1.2%+16.7%+19.8%
November 5, 2015November 4, 2015 MPWR Sale $67,145 −1.3%+19.8%+21.6%
August 11, 2015August 10, 2015 MPWR Sale $78,079 +24.4%+38.4%+37.5%
August 6, 2015August 4, 2015 MPWR Sale $205,047 +21.9%+36.7%+38.6%
May 6, 2015May 4, 2015 MPWR Sale $209,380 −1.8%+21.5%+24.2%
February 5, 2015February 3, 2015 MPWR Sale $1,099,171 +6.0%+26.6%+26.5%
November 6, 2014November 4, 2014 MPWR Sale $121,257 +7.9%+40.9%+39.2%
February 21, 2014February 20, 2014 MPWR Sale $143,490 +5.7%+32.2%+33.2%
February 18, 2014February 14, 2014 MPWR Sale $386,100 +6.7%+33.1%+29.3%
November 22, 2013November 22, 2013 MPWR Sale $150,823 +8.9%+30.1%+30.6%
August 9, 2013August 8, 2013 MPWR Sale $50,627 +4.8%+33.2%+31.8%
May 30, 2013May 28, 2013 MPWR Sale $482,180 +22.1%+38.5%+44.0%
May 8, 2013May 6, 2013 MPWR Sale $294,591 +13.8%+35.6%+32.1%
May 6, 2013May 2, 2013 MPWR Sale $30,891 +2.8%+33.0%+33.5%
February 8, 2013February 6, 2013 MPWR Sale $86,466 −10.6%+16.0%+19.8%
February 6, 2013February 4, 2013 MPWR Sale $34,423 −9.8%+16.8%+16.4%
December 3, 2012November 29, 2012 MPWR Sale $420,000 +9.1%+29.9%+35.4%
November 14, 2012November 12, 2012 MPWR Sale $17,134 +31.4%+49.8%+45.3%
November 9, 2012November 8, 2012 MPWR Sale $28,535 +24.9%+45.3%+44.6%
November 5, 2012November 1, 2012 MPWR Sale $18,155 +26.1%+45.4%+40.2%
August 10, 2012August 9, 2012 MPWR Sale $38,716 −6.4%+24.2%+22.0%
August 3, 2012August 2, 2012 MPWR Sale $23,353 −5.0%+27.5%+17.8%
May 14, 2012May 10, 2012 MPWR Sale $14,442 −4.5%−5.8%−2.7%
May 8, 2012May 8, 2012 MPWR Sale $24,417 −5.5%−1.5%+1.0%
May 2, 2012May 2, 2012 MPWR Sale $19,152 −7.6%+3.0%+1.5%
February 29, 2012February 28, 2012 MPWR Sale $321,375 +4.7%+23.0%+20.6%
February 13, 2012February 10, 2012 MPWR Sale $12,561 +18.6%+34.8%+38.1%
February 2, 2012February 2, 2012 MPWR Sale $17,326 +19.6%+27.8%+30.1%
November 2, 2011November 2, 2011 MPWR Sale $10,779 +27.9%+43.8%+44.8%
August 3, 2011August 2, 2011 MPWR Sale $11,862 −11.9%+34.8%+36.9%
May 10, 2011May 10, 2011 MPWR Sale $11,217 −11.0%+26.4%+25.3%
May 3, 2011May 3, 2011 MPWR Sale $20,381 −7.5%+24.8%+25.1%
March 9, 2011February 18, 2011 MPWR Sale $23,360 +12.8%+23.8%+5.3%
February 10, 2011February 10, 2011 MPWR Sale $10,971 +1.1%+6.5%+3.9%
November 12, 2010November 10, 2010 MPWR Sale $16,032 −16.0%−30.7%−29.6%
August 13, 2010August 12, 2010 MPWR Sale $12,861 −18.1%−40.5%−38.1%
May 12, 2010May 11, 2010 MPWR Sale $15,130 −11.1%−39.3%−43.7%

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 Tseng Saria traded and do not suggest the use of non-public information. How every insider compares · the insider trading backtest.