undamentalytics Newsletter

Leach Jacob Steven: insider trades

Officer, Director at 2 companies we cover. 2 open-market purchases and 17 sales not made under a pre-set plan, reported from March 15, 2017 to November 10, 2025.

Would copying Leach Jacob Steven’s purchases have beaten the S&P 500?

Too few purchases to judge. None of their purchases has 12 months of prices after the report; we judge insiders once they have 20. The figures below can swing a long way on a handful of trades. Buying each purchase the day after it was reported, an equal amount each, and holding it 12 months or until they reported a sale would have turned $10,000 on November 11, 2025 into $14,475 by November 2, 2026, +46.5% a year. The copy held shares only 100% of the time, so the fair comparison is the S&P 500 on those same days with Treasury bills otherwise: $11,195, +12.4% a year (the S&P 500 held throughout made $11,195, +12.4% a year). Beta against the index was 0.63. After their sales, the shares moved −1.6% against the index over 12 months on average (a negative figure means selling was the right call); 59% 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.

$0$5.0k$10.0k$15.0k 20252026 $14.5k$11.2k$11.2k
Copying Leach Jacob StevenS&P 500, same days investedS&P 500, held throughout $10,000 copying Leach Jacob Steven’s open-market purchases from November 11, 2025, before costs and taxes, marked weekly. Each purchase gets the same starting stake, bought at the close of the first trading day after the report and sold 12 months later or the day after a reported sale of that stock; uninvested money earns the Treasury bill rate. “Same days invested” holds the S&P 500 only on the days the copy held shares, Treasury bills otherwise.
Return a year, copying
+46.5%
S&P 500, same days invested
+12.4% (held throughout +12.4%)
Time in shares
100%
Sharpe ratio (S&P 500)
1.11 (0.68)
Biggest drop (S&P 500)
−23% (−9%)
Market sensitivity (beta)
0.63
Purchases copied
1

Trade by trade

Leach Jacob Steven: trades against the S&P 500 afterwards
MeasuredTrades countedAverage vs S&P 500MedianWent the right wayYearst-statisticp-valueEvidence
Purchases, 3 months after the report 1 +11.9% +11.9% 100% 1 — — Not enough years
Purchases, 6 months after the report 1 −10.7% −10.7% 0% 1 — — 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 17 +3.6% −0.5% 53% 7 1.23 0.26 No reliable evidence
Sales, 12 months after the report 17 −1.6% −8.3% 59% 7 0.16 0.88 No reliable evidence
Sales, 12 months after the trade 17 −2.4% −12.8% 65% 7 0.07 0.95 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
Dexcom DXCM President & COO117March 15, 2017November 10, 2025
Senestech, Inc. SNES —10August 18, 2021August 18, 2021

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
November 10, 2025November 10, 2025 DXCM Purchase $1,001,761 +11.9%not yetnot yet
March 14, 2025March 12, 2025 DXCM Sale $990,669 +9.7%−23.2%−29.1%
January 30, 2025January 29, 2025 DXCM Sale $228,921 −0.5%−33.4%−31.8%
December 17, 2024December 16, 2024 DXCM Sale $57,191 +1.5%−29.0%−26.6%
September 11, 2024September 9, 2024 DXCM Sale $51,586 +7.9%−8.3%−12.8%
June 11, 2024June 10, 2024 DXCM Sale $85,712 −44.9%−41.9%−43.1%
March 14, 2024March 12, 2024 DXCM Sale $1,967,628 −17.6%−56.1%−58.1%
January 17, 2024January 16, 2024 DXCM Sale $491,800 +0.2%−60.5%−58.0%
September 13, 2021September 9, 2021 DXCM Sale $683,748 −4.0%−23.3%−24.6%
August 18, 2021August 16, 2021 SNES Purchase $229,000 not yetnot yetnot yet
March 12, 2021March 10, 2021 DXCM Sale $1,942,711 +5.4%+5.9%+4.5%
September 11, 2020September 9, 2020 DXCM Sale $1,537,438 −20.3%+4.6%+3.5%
March 13, 2020March 11, 2020 DXCM Sale $1,828,783 +68.3%+7.2%−0.8%
September 11, 2019September 9, 2019 DXCM Sale $706,113 +39.5%+147.5%+153.8%
March 13, 2019March 12, 2019 DXCM Sale $1,221,568 −3.8%+68.6%+75.5%
September 12, 2018September 10, 2018 DXCM Sale $663,309 −6.8%−2.7%−5.2%
August 28, 2018August 24, 2018 DXCM Sale $2,846,211 −6.9%+18.3%+26.6%
May 10, 2018May 8, 2018 DXCM Sale $1,117,548 +37.9%+32.7%+28.1%
March 15, 2017March 9, 2017 DXCM Sale $1,654,901 −5.0%−32.9%−42.5%

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