Flagship Pioneering, LLC — 13F Holdings & Portfolio
CIK 1400240 · latest 13F-HR filed 2026-08-14
Flagship Pioneering, LLC manages $1.54B in 13F-reported U.S. long-equity assets across 7 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are GENB (68.66%), MRNA (21.05%), SANA (5.67%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 0 new positions and exited 0; 3 existing positions rose in reported value and 1 fell.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
Long-equity book
Distinct positions
Filed 2026-08-14
vs 2026-03-31
Portfolio charts
Latest quarter's book, what changed, and how the portfolio has evolved across filings.
Portfolio map
Q2 26Box size = position value; colour = change in share count vs the prior quarter (green added, red trimmed, blue new). Rows split across managers or share classes are combined. Click a box for the stock.
Sector mix
% of 13F valueSectors from each company's SIC code; funds and ETFs grouped separately.
Biggest buys and sells
Q1 26 → Q2 26Estimated from the change in shares held × the quarter-end price, so price moves alone don't count as buying. New and exited positions are included.
13F assets and positions
4 quartersTotal reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.
Top positions over time
reported valueThe eight largest current positions, valued at each quarter end.
Concentration
top 10 = 100%Cumulative share of the portfolio held in the largest N positions.
SUITE 800E
CAMBRIDGE, MA 02142-1234
| Name | Title / Status | Ownership | Type |
|---|---|---|---|
| AFEYAN, NOUBAR, B Control | MEMBER | General partner | Individual |
| AFEYAN, NOUBAR, B Control | MEMBER | General partner | Individual |
| FLAGSHIP PIONEERING FUTURES, LLC Control | MANAGER | Less than 5% | Domestic Entity |
| FLAGSHIP PIONEERING HOLDINGS, INC. | MEMBER | 75% or more | Domestic Entity |
Quarter-over-quarter changes
Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.
Top Adds (vs prior quarter)
- GENERATE BIOMEDICINES INC$273.9M +35.0%
- MODERNA INC$89.1M +37.9%
- SANA BIOTECHNOLOGY INC$15.3M +21.2%
Flagship Pioneering, LLC Holdings (2026-06-30)
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | GENERATE BIOMEDICINES INC | GENB | 370920100 | $1.06B | 68.66% | 62,673,117 | SH |
| 2 | MODERNA INC | MRNA | 60770K107 | $324.1M | 21.05% | 4,628,225 | SH |
| 3 | SANA BIOTECHNOLOGY INC | SANA | 799566104 | $87.3M | 5.67% | 25,001,856 | SH |
| 4 | FOGHORN THERAPEUTICS INC | FHTX | 344174107 | $61.8M | 4.02% | 12,674,120 | SH |
| 5 | SERES THERAPEUTICS INC | MCRB | 81750R201 | $5.8M | 0.38% | 733,207 | SH |
| 6 | SERES THERAPEUTICS INC | MCRB | 81750R201 | $3.3M | 0.22% | 422,643 | SH |
| 7 | MODERNA INC | MRNA | 60770K107 | $274.8K | 0.02% | 3,924 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-14 | $1.54B | 7 | 0001193125-26-352122 |
| 2026-03-31 | 2026-05-15 | $1.16B | 7 | 0001193125-26-226588 |
| 2025-12-31 | 2026-02-17 | $324.0M | 6 | 0001193125-26-054539 |
| 2025-09-30 | 2025-11-14 | $292.6M | 8 | 0001193125-25-282859 |
CAMBRIDGE, MA 02142