Institutional Manager · CIK 0001400240
Flagship Pioneering Inc.
Cambridge, MA · File #028-17559
Latest AUM
$324.0M
Positions
5
Top-10 Concentration
100.0%
Filings
9
Portfolio Value Over Time
2024-03
2024-06
2024-09
2024-12
2025-03
2025-06
2025-09
2025-12
Biggest QoQ Changes
Ranked by conviction flow (share change × current price) so mark-to-market moves don't dominate. Price effect column shows how much of the $ change was just the stock moving.
| Action | Issuer | Ticker / CUSIP | Δ Shares | Flow ($) | Price Effect |
|---|---|---|---|---|---|
| ADD | Moderna Inc | MRNA | +4,624,301 | +$136.4M | +$14,362 |
| ADD | Foghorn Therapeutics Inc | FHTX | +9,330,878 | +$50.4M | +$1.7M |
| ADD | Sana Biotechnology Inc | SANA | +9,092,678 | +$37.0M | +$8.3M |
| REDUCE | Seres Therapeutics Inc | MCRB | -310,564 | -$4.6M | -$3.2M |
Sector Allocation
Filing History
- 13F HOLDINGS REPORTQ/E Dec 20255 pos · $324.0M
- 13F HOLDINGS REPORTQ/E Sep 20258 pos · $292.6M
- 13F HOLDINGS REPORTQ/E Jun 20258 pos · $268.5M
- 13F HOLDINGS REPORTQ/E Mar 20258 pos · $235.8M
- 13F HOLDINGS REPORTQ/E Dec 202410 pos · $334.2M
- 13F HOLDINGS REPORTQ/E Sep 202412 pos · $591.9M
- 13F HOLDINGS REPORTQ/E Jun 202412 pos · $843.4M
- 13F HOLDINGS REPORTQ/E Mar 202413 pos · $1.52B
- 13F HOLDINGS REPORTQ/E Dec 202318 pos · $1.38B
Top 6 Holdings — Dec 2025
| # | Issuer | Ticker | Shares | Value | % of Portfolio |
|---|---|---|---|---|---|
| 1 | Moderna Inc | MRNA | 4,628,225 | $136.5M | 42.12% |
| 2 | Sana Biotechnology Inc | SANA | 25,001,856 | $101.8M | 31.40% |
| 3 | Foghorn Therapeutics Inc | FHTX | 12,674,120 | $68.4M | 21.12% |
| 4 | Seres Therapeutics Inc | MCRB | 733,207 | $10.9M | 3.38% |
| 5 | Seres Therapeutics Inc | MCRB | 422,643 | $6.3M | 1.94% |
| 6 | Moderna Inc | MRNA | 3,924 | $115,719 | 0.04% |