IGM Biosciences, Inc.
IGM Biosciences, Inc. (IGMS) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · IGMS · as of Jun 30, 2025
Ownership Breakdown
67
Institutional Holders
▼ 13 vs Q1
$17.88M
Total Inst. Value
▼ $2.61M vs Q1
61.02M
Shares Outstanding
freeFloat 48.21%
15.96M
13F Shares Held
▼ 1.86M vs Q1
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
IGMS largest shareholders · institutional ownership
Q2 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
BAKER BROS. ADVISORS LP pharmaceutical preparations | 4.10M | 6.66% | 6.66% | $4.59B | Aug 14, 2025 | ▲ 953 |
SIREN, L.L.C. pharmaceutical preparations | 3.26M | 5.30% | 5.30% | $3.65B | Aug 13, 2025 | — held |
REDMILE GROUP, LLC pharmaceutical preparations | 2.95M | 4.80% | 4.80% | $3.31B | Aug 14, 2025 | — held |
SANOFI pharmaceutical preparations | 1.44M | 2.34% | 2.34% | $1.61B | Jul 29, 2025 | — held |
GOLDMAN SACHS GROUP INC pharmaceutical preparations | 855.3K | 1.39% | 1.39% | $957.92M | Aug 14, 2025 | ▲ 61.9K |
VANGUARD GROUP INC pharmaceutical preparations | 767.2K | 1.25% | 1.25% | $859.21M | Aug 11, 2025 | ▼ 108.4K |
BLACKROCK, INC. pharmaceutical preparations | 385.5K | 62.72% | 62.72% | $431.73M | Aug 12, 2025 | ▼ 645.0K |
MILLENNIUM MANAGEMENT LLC pharmaceutical preparations | 275.1K | 44.76% | 44.76% | $308.13M | Aug 14, 2025 | ▲ 275.1K |
GEODE CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 213.3K | 34.70% | 34.70% | $238.98M | Aug 8, 2025 | ▼ 212.4K |
JANE STREET GROUP, LLC pharmaceutical preparations | 181.0K | 29.45% | 29.45% | $202.70M | Aug 14, 2025 | NEW |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q2 2025 vs prior quarter
Q2 2025
15
Increased
+550.0K shares5
New Positions
first time holders24
Decreased
−1.86M shares0
Sold Out
fully exitedNet shares change (top 50)
1.31M
+550.0K / −1.86M
Net new holders
-4
5 new / 0 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
IGMS insider trading · insider activity
Source: SEC Form 4
Insiders have been primarily selling shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
0
Buy transactions
18
Sell transactions
0.00
Buy/Sell ratio
$47M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
BAKER BROS. ADVISORS LP Former 10% owner and director | Aug 14, 2025 | U-Tender | 3,763,362 | $1.25 | $4.69M | 0 | Form 4 ↗ |
BAKER BROS. ADVISORS LP Former 10% owner and director | Aug 14, 2025 | U-Tender | 9,886,217 | — | — | 0 | Form 4 ↗ |
Redmile Group, LLC
| Aug 14, 2025 | D-Return | 2,964,843 | $1.25 | $3.70M | 0 | Form 4 ↗ |
Redmile Group, LLC
| Aug 14, 2025 | D-Return | 7,199,325 | — | — | 0 | Form 4 ↗ |
Redmile Group, LLC
| Aug 14, 2025 | D-Return | 667,666 | $0.01 | $6.7K | 0 | Form 4 ↗ |
Hambleton Julie director | Aug 14, 2025 | D-Return | 2,000 | — | — | 0 | Form 4 ↗ |
Lee Michael Stewart director | Aug 14, 2025 | D-Return | 12,712 | $1.25 | $15.9K | 0 | Form 4 ↗ |
Topsoe Holding A/S 10 percent owner | Aug 14, 2025 | D-Return | 5,044,295 | — | — | 0 | Form 4 ↗ |
Topsoe Holding A/S 10 percent owner | Aug 14, 2025 | D-Return | 10,400,564 | — | — | 0 | Form 4 ↗ |
Topsoe Jakob Haldor
| Aug 14, 2025 | D-Return | 5,044,295 | — | — | 0 | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
IGM Biosciences, Inc. (IGMS) is primarily owned by institutional investors, who hold approximately 26.2% of total shares outstanding. Company insiders own approximately 51.79%, while retail and public investors account for the remaining 22.05%.
The largest institutional shareholder of IGM Biosciences, Inc. is BAKER BROS. ADVISORS LP, holding approximately 4.10 million shares — equal to 6.66% of outstanding shares — as of June 30, 2025.
A total of 67 institutional investors currently hold IGMS stock, with a combined institutional value of approximately $17,875,989 as of the most recent 13F filing period.
Frequently asked questions
IGMS ownershipIGM Biosciences, Inc. (IGMS) is primarily owned by institutional investors, who hold approximately 26.2% of shares. The largest shareholder is BAKER BROS. ADVISORS LP with a 6.66% stake. Company insiders hold 51.79%. Data sourced from SEC Form 13F as of June 30, 2025.