13F

Investor

Flagship Pioneering, LLC

CIK 0001400240 · filed 2026-05-15 · SEC filing

13F book

$1.16B

Positions

5

1 new · 0 sold

Largest name

67.4%

Generate Biomedicines, Inc. · GENB

Est. mark

$54.1M

Price effect on 4 names still held. Flow $783.4M.
NameTickerSharesValueWeightEst. markChange
Generate Biomedicines, Inc.GENB62.7M$783.4M67.4%New
Moderna, Inc.MRNA4.63M$235.3M20.3%$98.7MHeld
Sana Biotechnology, Inc.SANA25M$72M6.2%−$29.8MHeld
Foghorn Therapeutics Inc.FHTX12.7M$60.6M5.2%−$7.86MHeld
Seres Therapeutics, Inc.MCRB1.16M$10.3M0.9%−$6.98MHeld

Positions as of Q1 2026. 13F filings arrive up to 45 days after quarter-end and omit shorts. Values are quarter-end marks, as filed. Estimated mark is the price effect on shares still held — not realized P&L or investment advice.