undamentalytics Newsletter

Day Christopher: insider trades

Officer at Ambarella Inc. No open-market purchases and 107 sales not made under a pre-set plan, reported from June 12, 2013 to June 20, 2025.

What happened after Day Christopher’s sales?

After their sales, the shares moved −0.1% against the index over 12 months on average (a negative figure means selling was the right call); 65% 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

Day Christopher: 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 107 +1.6% −4.2% 55% 13 0.44 0.66 No reliable evidence
Sales, 12 months after the report 107 −0.1% −15.6% 65% 13 0.24 0.81 No reliable evidence
Sales, 12 months after the trade 107 −0.2% −15.2% 63% 13 0.17 0.87 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
Ambarella Inc AMBA VP, Marketing0107June 12, 2013June 20, 2025

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
June 20, 2025June 17, 2025 AMBA Sale $17,873 +60.8%−1.4%+6.8%
March 20, 2025March 18, 2025 AMBA Sale $26,355 −11.7%−16.6%−15.1%
March 7, 2025March 6, 2025 AMBA Sale $45,962 +3.8%−11.7%−20.3%
January 7, 2025January 3, 2025 AMBA Sale $97,391 −32.0%−29.3%−26.9%
December 20, 2024December 18, 2024 AMBA Sale $70,047 −23.7%−19.9%−14.2%
December 18, 2024December 16, 2024 AMBA Sale $36,348 −17.6%−14.3%−20.4%
December 3, 2024December 2, 2024 AMBA Sale $91,518 −23.7%−6.0%−13.5%
October 4, 2024October 3, 2024 AMBA Sale $168,432 +29.2%+31.5%+23.4%
September 19, 2024September 17, 2024 AMBA Sale $25,860 +23.0%+37.9%+33.0%
July 10, 2024July 8, 2024 AMBA Sale $86,817 −8.0%−4.8%−3.9%
June 20, 2024June 18, 2024 AMBA Sale $27,019 −6.4%+4.4%−17.7%
March 20, 2024March 18, 2024 AMBA Sale $20,496 +5.0%−1.1%−0.4%
March 11, 2024March 8, 2024 AMBA Sale $17,262 −1.9%−11.7%−18.0%
December 21, 2023December 19, 2023 AMBA Sale $22,694 −29.6%−10.4%−15.9%
September 20, 2023September 18, 2023 AMBA Sale $20,112 +7.6%−31.1%−34.8%
July 14, 2023July 12, 2023 AMBA Sale $188,512 −31.8%−52.5%−53.0%
June 20, 2023June 20, 2023 AMBA Sale $30,019 −32.8%−57.7%−58.6%
June 14, 2023June 13, 2023 AMBA Sale $260,820 −34.8%−60.7%−60.7%
June 12, 2023June 9, 2023 AMBA Sale $355,609 −36.4%−60.7%−58.3%
April 14, 2023April 13, 2023 AMBA Sale $254,457 +11.7%−58.9%−57.4%
March 17, 2023March 17, 2023 AMBA Sale $185,977 −5.5%−68.9%−69.5%
March 10, 2023March 9, 2023 AMBA Sale $29,446 −0.2%−66.2%−63.6%
December 20, 2022December 16, 2022 AMBA Sale $255,609 −9.9%−48.6%−49.3%
December 15, 2022December 14, 2022 AMBA Sale $211,883 −8.6%−49.3%−48.1%
September 20, 2022September 16, 2022 AMBA Sale $42,378 +26.8%−33.8%−29.7%
June 17, 2022June 16, 2022 AMBA Sale $46,654 −10.6%−1.1%+3.7%
March 18, 2022March 16, 2022 AMBA Sale $675,336 −13.8%−10.0%−10.4%
March 14, 2022March 14, 2022 AMBA Sale $60,191 −9.0%−6.3%−1.5%
December 28, 2021December 27, 2021 AMBA Sale $148,420 −44.8%−42.0%−43.5%
December 17, 2021December 16, 2021 AMBA Sale $168,085 −45.7%−40.6%−37.8%
December 8, 2021December 7, 2021 AMBA Sale $726,419 −49.3%−48.1%−50.0%
December 7, 2021December 3, 2021 AMBA Sale $160,318 −50.2%−49.1%−50.7%
June 30, 2021June 29, 2021 AMBA Sale $84,888 +46.9%−30.1%−26.7%
June 17, 2021June 16, 2021 AMBA Sale $146,509 +46.6%−20.6%−19.9%
June 16, 2021June 14, 2021 AMBA Sale $148,260 +45.0%−22.8%−23.0%
April 1, 2021March 31, 2021 AMBA Sale $28,449 −6.4%−15.6%−12.0%
March 18, 2021March 16, 2021 AMBA Sale $1,132,172 −14.7%−22.1%−29.2%
March 11, 2021March 9, 2021 AMBA Sale $97,159 −19.2%−32.9%−28.0%
December 18, 2020December 16, 2020 AMBA Sale $342,140 +4.5%+92.0%+72.1%
December 10, 2020December 8, 2020 AMBA Sale $117,689 +15.7%+93.9%+113.7%
December 2, 2020November 30, 2020 AMBA Sale $106,626 +15.4%+93.3%+102.2%
September 30, 2020September 29, 2020 AMBA Sale $46,748 +59.8%+156.0%+164.9%
September 18, 2020September 16, 2020 AMBA Sale $47,649 +60.2%+158.9%+153.0%
June 30, 2020June 30, 2020 AMBA Sale $58,181 +7.1%+93.7%+91.9%
June 18, 2020June 16, 2020 AMBA Sale $46,656 +0.9%+64.2%+58.9%
April 1, 2020March 31, 2020 AMBA Sale $48,556 −27.5%+61.9%+50.5%
March 30, 2020March 27, 2020 AMBA Sale $38,439 −25.8%+50.5%+40.0%
March 19, 2020March 17, 2020 AMBA Sale $82,386 −14.2%+88.4%+109.3%
December 20, 2019December 20, 2019 AMBA Sale $59,842 +3.0%+40.9%+37.0%
December 19, 2019December 17, 2019 AMBA Sale $36,095 +2.6%+37.0%+41.1%
October 1, 2019September 30, 2019 AMBA Sale $218,488 −3.0%−25.0%−31.4%
September 18, 2019September 16, 2019 AMBA Sale $254,357 −18.7%−30.4%−34.4%
September 6, 2019September 4, 2019 AMBA Sale $23,782 −23.4%−41.4%−29.5%
June 26, 2019June 24, 2019 AMBA Sale $109,510 +38.6%−3.7%+4.5%
June 19, 2019June 18, 2019 AMBA Sale $57,485 +44.8%+4.3%+9.7%
April 2, 2019March 29, 2019 AMBA Sale $81,287 −5.7%+14.2%+14.9%
March 20, 2019March 18, 2019 AMBA Sale $159,936 −4.9%+8.8%+4.7%
March 11, 2019March 8, 2019 AMBA Sale $180,079 −7.4%+0.2%+6.0%
December 20, 2018December 18, 2018 AMBA Sale $42,788 +7.4%+34.2%+23.2%
December 6, 2018December 4, 2018 AMBA Sale $74,347 +8.5%+13.2%+13.1%
September 20, 2018September 19, 2018 AMBA Sale $54,437 +6.3%+62.1%+69.8%
September 10, 2018September 6, 2018 AMBA Sale $52,735 +5.3%+56.0%+54.3%
June 26, 2018June 22, 2018 AMBA Sale $134,728 −13.2%−0.9%−6.2%
June 20, 2018June 18, 2018 AMBA Sale $144,453 −20.7%−8.8%−7.2%
March 20, 2018March 16, 2018 AMBA Sale $53,707 −20.8%−26.8%−24.5%
December 20, 2017December 18, 2017 AMBA Sale $64,094 −12.9%−32.8%−32.1%
October 2, 2017September 29, 2017 AMBA Sale $128,675 +23.3%−41.8%−39.3%
September 20, 2017September 18, 2017 AMBA Sale $71,098 +20.0%−35.3%−41.7%
June 20, 2017June 16, 2017 AMBA Sale $74,423 −8.9%−25.5%−26.8%
March 31, 2017March 31, 2017 AMBA Sale $117,050 −16.4%−29.0%−26.8%
March 17, 2017March 16, 2017 AMBA Sale $67,035 −18.0%−23.0%−20.8%
March 14, 2017March 13, 2017 AMBA Sale $59,440 −13.9%−21.5%−24.9%
December 16, 2016December 16, 2016 AMBA Sale $89,772 −4.2%−14.2%−13.8%
October 3, 2016September 29, 2016 AMBA Sale $296,135 −32.8%−52.5%−50.2%
September 29, 2016September 27, 2016 AMBA Sale $417,524 −30.4%−52.9%−47.6%
September 23, 2016September 21, 2016 AMBA Sale $134,000 −22.3%−49.9%−50.0%
September 20, 2016September 16, 2016 AMBA Sale $95,512 −24.2%−50.0%−51.1%
June 30, 2016June 30, 2016 AMBA Sale $59,647 +41.7%−23.1%−22.2%
June 20, 2016June 16, 2016 AMBA Sale $73,018 +24.7%−24.9%−26.9%
March 31, 2016March 29, 2016 AMBA Sale $78,822 +12.6%+6.9%+8.3%
March 18, 2016March 16, 2016 AMBA Sale $54,752 +33.1%+24.3%+29.0%
December 23, 2015December 21, 2015 AMBA Sale $52,299 −24.3%−17.4%−21.0%
December 18, 2015December 16, 2015 AMBA Sale $161,672 −33.0%−21.0%−15.2%
December 10, 2015December 8, 2015 AMBA Sale $44,562 −35.4%−22.4%−10.5%
October 1, 2015September 30, 2015 AMBA Sale $58,742 −11.8%+12.4%+8.2%
September 17, 2015September 16, 2015 AMBA Sale $133,104 −25.6%−15.8%−12.7%
June 18, 2015June 16, 2015 AMBA Sale $765,263 −33.3%−56.4%−56.4%
June 10, 2015June 10, 2015 AMBA Sale $115,000 −30.0%−55.3%−56.4%
June 9, 2015June 5, 2015 AMBA Sale $141,678 −32.2%−56.4%−57.9%
April 1, 2015March 31, 2015 AMBA Sale $75,500 +35.9%−42.3%−42.6%
March 30, 2015March 26, 2015 AMBA Sale $354,088 +35.4%−42.6%−41.7%
March 23, 2015March 20, 2015 AMBA Sale $177,550 +38.6%−44.5%−45.3%
March 19, 2015March 17, 2015 AMBA Sale $147,102 +64.2%−45.3%−44.3%
March 18, 2015March 16, 2015 AMBA Sale $66,645 +80.9%−42.4%−44.5%
March 13, 2015March 11, 2015 AMBA Sale $135,900 +68.9%−44.5%−42.8%
December 31, 2014December 30, 2014 AMBA Sale $109,800 +42.8%+6.2%+6.8%
December 30, 2014December 26, 2014 AMBA Sale $136,781 +45.0%+8.7%+3.9%
December 23, 2014December 22, 2014 AMBA Sale $183,105 +35.7%+11.5%+13.5%
December 18, 2014December 16, 2014 AMBA Sale $135,667 +50.4%+22.6%+16.9%
September 30, 2014September 29, 2014 AMBA Sale $55,122 +15.8%+38.7%+27.9%
September 24, 2014September 23, 2014 AMBA Sale $104,750 +24.6%+46.7%+53.0%
September 17, 2014September 16, 2014 AMBA Sale $46,619 +15.6%+78.2%+89.5%
June 18, 2014June 16, 2014 AMBA Sale $36,241 +34.6%+298.7%+317.3%
March 20, 2014March 18, 2014 AMBA Sale $19,292 +0.9%+144.2%+116.6%
December 19, 2013December 17, 2013 AMBA Sale $15,440 −0.3%+65.3%+72.9%
July 2, 2013June 28, 2013 AMBA Sale $78,375 +11.7%+65.9%+60.9%
June 12, 2013June 10, 2013 AMBA Sale $343,600 −1.1%+36.7%+30.9%

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