InsiderSource

ARCH Venture Partners IX, LLC

10% Owner · SEC CIK 1666306
Insider at LYEL Lyell Immunopharma, Inc. BOLD Boundless Bio, Inc. SANA Sana Biotechnology, Inc. VIR Vir Biotechnology, Inc. BEAM Beam Therapeutics Inc. KRTX Karuna Therapeutics, Inc. GOSS Gossamer Bio, Inc.
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Buy track record

How this insider's open-market purchases have performed
0%
of buys now in profit
0 up · 6 down
Avg return since buy−62.3%
Median return−56.5%
Best trade−39.9%
Worst trade−89.6%
Buys scored6 (+1 n/a)
Average return by holding period — separates good entry timing from riding one long winner
After 1 month +4.1% 33% won · 6 trades
After 3 months −9.7% 50% won · 6 trades
After 6 months −20.9% 20% won · 5 trades
After 12 months −24.6% 20% won · 5 trades
DateCompany90d trendBuy priceValueΔOwn1M3M6M12MTo date
Mar 6, 2026 LYEL $26 $12.5M +52% −3.4% −45.2% — — −39.9%
Apr 2, 2024 BOLD $16 $1.07M +11% −33.6% −68.4% −77.1% −89.1% −89.6%
Apr 2, 2024 BOLD $16 $2.13M +13% −33.6% −68.4% −77.1% −89.1% −89.6%
Feb 8, 2024 SANA $6 $2M +3.5% +54.2% +54.1% −24.4% −55.6% −56.5%
Feb 8, 2024 SANA $6 $4M +6.2% +54.2% +54.1% −24.4% −55.6% −56.5%
Oct 16, 2019 VIR $20 $20M NEW −13.2% +16.0% +98.2% +166.5% −41.8%
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 6 scored trades, treat this as a small sample, not a verdict.
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Open-market buys
$43.3M
7 trades
Open-market sells
$0
0 trades
Net flow
+$43.3M
Net buying
Total filings
44
transactions shown

Full transaction history

All Form 4 activity across every company, newest first
View on SEC EDGAR ↗
LYEL
Lyell Immunopharma, Inc.
Buy ARCH Venture Partners IX, LLC · 10% Owner · Open-market purchase · filed Mar 9, 2026 ΔOwn +52%

Arch Venture Partners Ix, Llc, LYEL's 10% owner, spent $12.5M of their own money on 488,090 shares at $26, growing their stake 52%.

+$12.5M
488,090 sh @ $26
BOLD
Boundless Bio, Inc.
Buy ARCH Venture Fund IX, L.P. · 10% Owner · Open-market purchase · filed Apr 4, 2024 ΔOwn +11%

Arch Venture Fund Ix, L.p., BOLD's 10% owner, spent $1.07M of their own money on 66,667 shares at $16, growing their stake 11%.

+$1.07M
66,667 sh @ $16
BOLD
Boundless Bio, Inc.
Buy ARCH Venture Fund IX, L.P. · 10% Owner · Open-market purchase · filed Apr 4, 2024 ΔOwn +13%

Arch Venture Fund Ix, L.p., BOLD's 10% owner, spent $2.13M of their own money on 133,333 shares at $16, growing their stake 13%.

+$2.13M
133,333 sh @ $16
SANA
Sana Biotechnology, Inc.
Buy ARCH Venture Fund X, L.P. · 10% Owner · Open-market purchase · filed Feb 12, 2024 ΔOwn +3.5%

Arch Venture Fund X, L.p., SANA's 10% owner, spent $2M of their own money on 363,637 shares at $6, growing their stake 4%.

+$2M
363,637 sh @ $6
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SANA
Sana Biotechnology, Inc.
Buy ARCH Venture Fund X, L.P. · 10% Owner · Open-market purchase · filed Feb 12, 2024 ΔOwn +6.2%

Arch Venture Fund X, L.p., SANA's 10% owner, spent $4M of their own money on 727,272 shares at $6, growing their stake 6%.

+$4M
727,272 sh @ $6

Frequently asked questions

How is ARCH Venture Partners IX, 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 ARCH Venture Partners IX, 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.