FindingSAVNG Research · September 10, 2026Pre-registered

When an insider raises their stake by 30% or more during a sell-off

The claim. If you had bought the same stock the day after every stake increase of 30%+ became public, from 2006 to 2026, and held for three months, you would have beaten small caps by +7.5 pts on average when the market was in a sell-off (2,805 trades, very unlikely to be luck) and by +1.2 pts when it was calm (6,914 trades, unlikely to be luck). All states together: +3.0 pts across 9,719 trades.

The size of the commitment matters. Buys that raised the insider's existing holding by at least 30% are the strongest single signal we have found, and the Industrials cell was pre-registered before we looked.

How we tested it
  • Trades: every open-market insider purchase reported to the SEC on Form 4 from 2006 onward that passes our routine-versus-opportunistic filter; for this piece, the buyer raised their existing holding by at least 30% (and at most 30ã—).
  • Entry: first session after the filing became public. Held 63 trading days (about three months).
  • Benchmark: IWM (small caps), because insider-buy candidates skew small and cheap; beating the S&P alone would just be that tilt.
  • Market state: stress = SPY at least 10% below its trailing 1-year high on the entry day; calm otherwise.
  • Statistics: clustered by company (one vote per company) — five insiders buying the same stock in the same week count once. Cells under 40 trades or 15 companies are shown but greyed. No trading costs deducted.
  • What is excluded: companies without a ten-year price history (delisted names are the main gap; see the survivorship note on the evidence page).
Reproduce: node savng-insider-history/sector-findings.js → reports/sector-findings.json (generated 2026-09-10); served at /research-data.
The picture
Software & IT services+22.1 pts n 68Medical devices+18.0 pts n 73Energy+16.2 pts n 119Tech hardware & semis+14.0 pts n 118Retail & consumer+10.5 pts n 135Biotech & pharma+9.5 pts n 69Industrials & manufacturing+9.0 pts n 397Finance & real estate+8.3 pts n 55Other+8.1 pts n 136Insurance+5.8 pts n 125Services+5.8 pts n 133Banks+4.4 pts n 719REITs+3.5 pts n 136Utilities+2.9 pts n 63

Three-month excess return versus small caps for stake increase of 30%+s made during sell-offs, by sector. Sectors with too few trades omitted from the chart, shown in the table.

Does it apply to your sector?
Sector (SEC industry group)In sell-offsIn calm marketsRead
Software & IT services +22.1 pts n 68 · t 2.6 −3.4 pts n 183 · t -0.8 Sell-offs only; loses in calm
Medical devices +18.0 pts n 73 · t 2.0 +0.9 pts n 127 · t 0.3 Sell-offs only
Construction +17.2 pts n 35 · t 3.1 −9.4 pts n 78 · t -1.7 Too few trades to say
Energy +16.2 pts n 119 · t 3.4 +0.2 pts n 259 · t -1.1 Sell-offs only
Tech hardware & semis +14.0 pts n 118 · t 2.8 −2.1 pts n 237 · t -1.1 Sell-offs only; loses in calm
Mining & metals +11.1 pts n 10 · t 0.4 −8.9 pts n 67 · t -1.6 Too few trades to say
Retail & consumer +10.5 pts n 135 · t 2.2 +0.7 pts n 306 · t 1.4 Sell-offs only
Biotech & pharma +9.5 pts n 69 · t 2.2 +9.7 pts n 304 · t 1.0 Sell-offs only
Industrials & manufacturing +9.0 pts n 397 · t 3.0 +0.2 pts n 895 · t 0.9 Sell-offs only
Finance & real estate +8.3 pts n 55 · t 1.8 −0.4 pts n 169 · t 0.6 No reliable edge
Other +8.1 pts n 136 · t 2.6 +1.4 pts n 221 · t 1.0 Sell-offs only
Telecom & media +7.5 pts n 16 · t 1.4 +1.1 pts n 47 · t -0.7 Too few trades to say
Insurance +5.8 pts n 125 · t 0.5 +0.1 pts n 198 · t 0.4 No reliable edge
Services +5.8 pts n 133 · t 1.2 +1.1 pts n 346 · t -0.1 No reliable edge
Banks +4.4 pts n 719 · t 1.6 +2.4 pts n 1,789 · t 5.3 Calm markets only
REITs +3.5 pts n 136 · t 0.7 +0.7 pts n 301 · t 0.7 No reliable edge
Utilities +2.9 pts n 63 · t 0.5 +3.2 pts n 172 · t 1.0 No reliable edge
Food, drink & tobacco +2.6 pts n 17 · t 1.2 +5.7 pts n 71 · t 0.6 Too few trades to say
Healthcare services +2.6 pts n 13 · t -0.2 +3.3 pts n 25 · t 0.2 Too few trades to say
Transport & logistics +1.7 pts n 43 · t 0.5 +2.3 pts n 111 · t 0.9 No reliable edge

t is the clustered t-statistic: above 2 means the result is unlikely to be luck; above 3, very unlikely. "n" is trades.

Where it applies today

Market state now: NORMAL — the S&P 500 is 3.1% below its one-year high (as of 2026-09-16). The calm column above is the one that applies today; the sell-off numbers are what to expect if conditions change.

Sectors under pressure right now (their own ETF is in a drawdown):

Mining & metals18.1% below its high Construction24.8% below its high Tech hardware & semis18.4% below its high · this signal in this sector's sell-offs: +14.0 pts Transport & logistics10.9% below its high · this signal in this sector's sell-offs: +1.7 pts Software & IT services10.9% below its high · this signal in this sector's sell-offs: +22.1 pts Medical devices19.5% below its high · this signal in this sector's sell-offs: +18.0 pts Retail & consumer11.5% below its high · this signal in this sector's sell-offs: +10.5 pts Utilities13.4% below its high · this signal in this sector's sell-offs: +2.9 pts

No buy in the last 45 days matches this definition among names we cover.

All live buys →The 20-year evidence pageMethodology
Where it does not apply
Stake increases in calm markets carry about a third of the edge. Very large percentage increases (from a near-zero holding) are excluded because they are not commitments, they are first positions.

SAVNG is an educational research publication, not a Registered Investment Adviser. Everything here is general-circulation information produced by an automated pipeline — the same for every reader — and is not personalized investment advice, an offer, or a recommendation to buy or sell any security. Any performance figure is hypothetical; past performance does not predict future results. Details.

Published by SAVNG Research. Every figure on this page is read from the study data at render time; if the study changes, the page changes with it.

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