Assembly Biosciences, Inc.
Assembly Biosciences, Inc. (ASMB) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · ASMB · as of Sep 30, 2025
Ownership Breakdown
59
Institutional Holders
▲ 25 vs Q2
$324.91M
Total Inst. Value
▲ $267.86M vs Q2
15.89M
Shares Outstanding
freeFloat 55.37%
12.48M
13F Shares Held
▲ 9.33M vs Q2
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
ASMB largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
GILEAD SCIENCES, INC. pharmaceutical preparations | 4.51M | 58.85% | 58.85% | $115.34B | Nov 13, 2025 | ▲ 2.30M |
FARALLON CAPITAL MANAGEMENT LLC pharmaceutical preparations | 1.23M | 16.03% | 16.03% | $31.43B | Feb 17, 2026 | NEW |
RA CAPITAL MANAGEMENT, L.P. pharmaceutical preparations | 1.02M | 13.33% | 13.33% | $26.12B | Nov 14, 2025 | NEW |
COMMODORE CAPITAL LP pharmaceutical preparations | 1.00M | 13.06% | 13.06% | $25.60B | Nov 14, 2025 | NEW |
JANUS HENDERSON GROUP PLC pharmaceutical preparations | 752.6K | 9.83% | 9.83% | $19.23B | Nov 14, 2025 | NEW |
VANGUARD GROUP INC pharmaceutical preparations | 502.1K | 6.56% | 6.56% | $12.85B | Nov 7, 2025 | ▲ 248.3K |
FRAZIER LIFE SCIENCES MANAGEMENT, L.P. pharmaceutical preparations | 456.2K | 5.96% | 5.96% | $11.68B | Nov 14, 2025 | NEW |
BLACKSTONE INC. pharmaceutical preparations | 447.8K | 5.85% | 5.85% | $11.46B | Nov 14, 2025 | NEW |
CAPTION MANAGEMENT, LLC pharmaceutical preparations | 349.8K | 4.57% | 4.57% | $8.95B | Nov 14, 2025 | NEW |
POINT72 ASSET MANAGEMENT, L.P. pharmaceutical preparations | 296.0K | 3.87% | 3.87% | $7.58B | Nov 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
Q3 2025 vs prior quarter
Q3 2025
17
Increased
+3.08M shares27
New Positions
first time holders2
Decreased
−16.1K shares0
Sold Out
fully exitedNet shares change (top 50)
+3.06M
+3.08M / −16.1K
Net new holders
+42
27 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
ASMB 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.
7
Buy transactions
0
Sell transactions
0.00
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
Gaggar Anuj Chief Medical Officer | Mar 29, 2026 | Award | 14,000 | — | — | 42.7K | Form 4 ↗ |
White Nicole S Chief Manufacturing Officer | Mar 29, 2026 | Award | 14,000 | — | — | 48.1K | Form 4 ↗ |
McHutchison John G director | Jun 4, 2026 | Award | 8,000 | $24.11 | $192.9K | 8.0K | Form 4 ↗ |
Mahony Susan director | Jun 4, 2026 | Award | 8,000 | $24.11 | $192.9K | 8.0K | Form 4 ↗ |
Johnson-Pratt Lisa director | Jun 4, 2026 | Award | 8,000 | $24.11 | $192.9K | 8.0K | Form 4 ↗ |
Houghton Michael director | Jun 4, 2026 | Award | 8,000 | $24.11 | $192.9K | 8.0K | Form 4 ↗ |
Consylman Gina director | Jun 4, 2026 | Award | 8,000 | $24.11 | $192.9K | 8.0K | Form 4 ↗ |
ALTIG ANTHONY E director | Jun 4, 2026 | Award | 8,000 | $24.11 | $192.9K | 8.0K | Form 4 ↗ |
Bjorkquist Jeanette M PFO and PAO | Mar 29, 2026 | Award | 3,500 | — | — | 14.6K | Form 4 ↗ |
Delaney William E IV Chief Scientific Officer | Mar 29, 2026 | Award | 14,000 | — | — | 60.3K | 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
Assembly Biosciences, Inc. (ASMB) is primarily owned by institutional investors, who hold approximately 78.5% of total shares outstanding. Company insiders own approximately 44.63%, while retail and public investors account for the remaining 0.00%.
The largest institutional shareholder of Assembly Biosciences, Inc. is GILEAD SCIENCES, INC., holding approximately 4.51 million shares — equal to 58.85% of outstanding shares — as of September 30, 2025.
A total of 59 institutional investors currently hold ASMB stock, with a combined institutional value of approximately $324,911,485 as of the most recent 13F filing period.
Frequently asked questions
ASMB ownershipAssembly Biosciences, Inc. (ASMB) is primarily owned by institutional investors, who hold approximately 78.5% of shares. The largest shareholder is GILEAD SCIENCES, INC. with a 58.85% stake. Company insiders hold 44.63%. Data sourced from SEC Form 13F as of September 30, 2025.