InsiderSource

Bain Capital Life Sciences Investors, LLC

10% Owner, Director · SEC CIK 1703031
Insider at RPID RAPID MICRO BIOSYSTEMS, INC. HTFL Heartflow, Inc. KLRA Kailera Therapeutics, Inc. SLDB Solid Biosciences Inc. OLMA Olema Pharmaceuticals, Inc. NAMS NewAmsterdam Pharma Co N.V. KYTX Kyverna Therapeutics, Inc. ANNX Annexon, Inc. XLO Xilio Therapeutics, Inc. SWTX SpringWorks Therapeutics, Inc. APTX Aptinyx Inc. ARQT Arcutis Biotherapeutics, Inc. DRNA Dicerna Pharmaceuticals Inc REPL Replimune Group, Inc. MRNS MARINUS PHARMACEUTICALS INC
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Buy track record

How this insider's open-market purchases have performed
23%
of buys now in profit
3 up · 10 down
Avg return since buy−36.7%
Median return−73.1%
Best trade+124.3%
Worst trade−94.2%
Buys scored13 (+3 n/a)
Average return by holding period — separates good entry timing from riding one long winner
After 1 month +18.6% 62% won · 13 trades
After 3 months −18.3% 25% won · 12 trades
After 6 months −36.0% 17% won · 12 trades
After 12 months +3.4% 33% won · 12 trades
DateCompany90d trendBuy priceValueΔOwn1M3M6M12MTo date
Apr 20, 2026 KLRA $16 $25M +7.4% −18.4% — — — −23.2%
Feb 19, 2025 SLDB $4 $4.03M +25% −25.5% −55.2% −10.4% −9.1% +10.4%
Jan 8, 2025 OLMA $6 $1.73M +4.0% −10.3% −46.8% −19.5% +344.7% +71.7%
Feb 12, 2024 KYTX $22 $9.9M +17% −3.1% −51.1% −78.2% −91.1% −73.1%
May 25, 2023 ANNX $2 $639.7K +5.6% +59.3% +32.9% +26.7% +136.2% +124.3%
Dec 10, 2021 XLO $10 $208.6K +0.8% +44.4% −24.1% −70.8% −77.1% −94.2%
Dec 10, 2021 XLO $10 $32.6K +0.1% +44.4% −24.1% −70.8% −77.1% −94.2%
Dec 9, 2021 XLO $10 $39.5K +0.1% +49.0% −23.9% −69.0% −76.8% −94.0%
Dec 8, 2021 XLO $10 $129.5K +0.5% +51.8% −28.1% −69.6% −76.2% −93.9%
Jul 19, 2021 RPID $20 $2M +1.2% −2.8% −8.9% −63.3% −78.3% −91.3%
Jul 28, 2020 ANNX $17 $6.8M +14% +34.9% +32.2% +25.0% +21.5% −73.8%
Feb 4, 2020 ARQT $17 $5M +8.0% +8.1% +0.1% −2.6% +36.1% −4.9%
Jul 24, 2018 REPL $15 $7.5M +21% +10.1% −22.4% −29.8% −12.5% −41.2%
How this is calculated. We score only open-market purchases (SEC code P) — the buys that carry real signal. Each trade's return is measured from the adjusted closing price on the purchase date to the latest close, accounting for stock splits and dividends. The 1M/3M/6M/12M columns show the same trade's return after each fixed holding period; a dash means that horizon hasn't elapsed yet or isn't priceable. Sales are excluded because insiders sell for many routine reasons. With only 13 scored trades, treat this as a small sample, not a verdict.
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Open-market buys
$77.7M
16 trades
Open-market sells
$357.5M
14 trades
Net flow
−$279.8M
Net selling
Total filings
42
transactions shown

Full transaction history

All Form 4 activity across every company, newest first
View on SEC EDGAR ↗
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ANNX
Annexon, Inc.
Buy Bain Capital Life Sciences Investors, LLC · 10% Owner · Open-market purchase · filed May 30, 2023 ΔOwn +5.6%

Bain Capital Life Sciences Investors, Llc, ANNX's 10% owner, spent $639.7K of their own money on 300,000 shares at $2, growing their stake 6%.

+$639.7K
300,000 sh @ $2
APTX
Aptinyx Inc.
Buy Bain Capital Life Sciences Investors, LLC · 10% Owner · Open-market purchase · filed Oct 27, 2020 ΔOwn +60%

Bain Capital Life Sciences Investors, Llc, APTX's 10% owner, spent $10M of their own money on 3.33M shares at $3, growing their stake 60%.

+$10M
3.33M sh @ $3
ANNX
Annexon, Inc.
Buy Bain Capital Life Sciences Investors, LLC · 10% Owner · Open-market purchase · filed Jul 28, 2020 ΔOwn +14%

Bain Capital Life Sciences Investors, Llc, ANNX's 10% owner, spent $6.8M of their own money on 400,000 shares at $17, growing their stake 14%.

+$6.8M
400,000 sh @ $17

Frequently asked questions

How is Bain Capital Life Sciences Investors, LLC's win rate calculated?

We take every open-market purchase (SEC code P) we can match to a stock price, then compare the split- and dividend-adjusted price on the purchase date to the most recent close. The win rate is the share of those buys currently trading above the purchase price. Sales and share grants are not scored.

Why are some buys not included in the score?

A purchase is excluded if we can't price it — for example if the ticker is missing from the filing, the company has been delisted, or the security isn't a common stock we can match to market data. Excluded counts are shown next to the scored total.

What do the 1M / 3M / 6M / 12M columns mean?

They show each purchase's return after a fixed holding period — one, three, six, and twelve months from the buy date — using split- and dividend-adjusted prices. This separates good entry timing from simply holding a long-running winner. A dash means that horizon hasn't elapsed yet for that trade, or the stock couldn't be priced at that date.

Does a high win rate mean I should copy this insider?

No. Past performance does not predict future results, sample sizes are often small, and an insider's edge in their own company doesn't transfer to yours. This is context, not a recommendation. InsiderSource is not investment advice.

Where does this data come from?

Trades come from Bain Capital Life Sciences Investors, LLC's SEC Form 4 filings on EDGAR. Prices come from public market data and are split/dividend-adjusted. Always verify against the original filings before acting.