Omeros Corporation
Omeros Corporation (OMER) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · OMER · as of Sep 30, 2025
Ownership Breakdown
149
Institutional Holders
▲ 12 vs Q2
$134.72M
Total Inst. Value
▲ $47.39M vs Q2
72.38M
Shares Outstanding
freeFloat 96.42%
32.85M
13F Shares Held
▲ 3.74M 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
OMER largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
BLACKROCK, INC. pharmaceutical preparations | 4.45M | 7.60% | 7.60% | $18.25B | Nov 12, 2025 | ▲ 401.2K |
INGALLS & SNYDER LLC pharmaceutical preparations | 4.11M | 7.01% | 7.01% | $16.84B | Nov 7, 2025 | ▲ 123.7K |
VANGUARD GROUP INC pharmaceutical preparations | 3.35M | 5.71% | 5.71% | $13.72B | Nov 7, 2025 | ▲ 63.4K |
MORGAN STANLEY pharmaceutical preparations | 1.99M | 3.40% | 3.40% | $8.16B | May 27, 2026 | ▲ 634.2K |
STIFEL FINANCIAL CORP pharmaceutical preparations | 1.81M | 3.09% | 3.09% | $7.43B | Nov 12, 2025 | ▲ 289.4K |
GEODE CAPITAL MANAGEMENT, LLC pharmaceutical preparations | 1.54M | 2.62% | 2.62% | $6.30B | Nov 12, 2025 | ▲ 165.5K |
POLAR ASSET MANAGEMENT PARTNERS INC. pharmaceutical preparations | 1.50M | 2.56% | 2.56% | $6.14B | Dec 1, 2025 | NEW |
POLAR ASSET MANAGEMENT PARTNERS INC. pharmaceutical preparations | 1.37M | 2.35% | 2.35% | $5.63B | Dec 1, 2025 | NEW |
STATE STREET CORP pharmaceutical preparations | 1.24M | 2.12% | 2.12% | $5.08B | Nov 14, 2025 | ▲ 39.6K |
AFFINITY ASSET ADVISORS, LLC pharmaceutical preparations | 1.13M | 1.94% | 1.94% | $4.65B | Nov 13, 2025 | ▲ 819.9K |
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
37
Increased
+5.23M shares3
New Positions
first time holders8
Decreased
−1.56M shares0
Sold Out
fully exitedNet shares change (top 50)
+3.67M
+5.23M / −1.56M
Net new holders
+32
3 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
OMER 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.
1
Buy transactions
3
Sell transactions
0.33
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 |
|---|---|---|---|---|---|---|---|
Cable Thomas J. director | May 22, 2026 | Sale | 7,500 | $11.61 | $87.0K | 35.1K | Form 4 ↗ |
Demopulos Gregory A MD Chairman, CEO & President | Feb 18, 2026 | Tax Withhold | 357,678 | $11.93 | $4.27M | 1.47M | Form 4 ↗ |
Borges David J. VP, Finance & CAO | Jan 13, 2026 | Sale | 30,000 | $12.31 | $369.3K | 0 | Form 4 ↗ |
Borges David J. VP, Finance & CAO | Jan 12, 2026 | Sale | 30,000 | $12.72 | $381.6K | 0 | Form 4 ↗ |
Demopulos Gregory A MD Chairman, CEO & President | Oct 13, 2025 | Gift | 600,000 | — | — | 1.43M | Form 4 ↗ |
Demopulos Gregory A MD Chairman, CEO & President | Oct 13, 2025 | Gift | 300,000 | — | — | 300.0K | Form 4 ↗ |
Demopulos Gregory A MD Chairman, CEO & President | Jun 30, 2025 | Award | 865,000 | $3.20 | $2.77M | 865.0K | Form 4 ↗ |
Cancelmo Peter B VP, General Counsel | Jun 30, 2025 | Award | 100,000 | $3.20 | $320.0K | 100.0K | Form 4 ↗ |
Borges David J. VP, Finance & CAO | Jun 30, 2025 | Award | 95,000 | $3.20 | $304.0K | 95.0K | Form 4 ↗ |
Shah Rajiv director | Jun 27, 2025 | Award | 15,000 | $3.20 | $48.0K | 15.0K | 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
Omeros Corporation (OMER) is primarily owned by institutional investors, who hold approximately 45.4% of total shares outstanding. Company insiders own approximately 3.58%, while retail and public investors account for the remaining 51.04%.
The largest institutional shareholder of Omeros Corporation is BLACKROCK, INC., holding approximately 4.45 million shares — equal to 7.60% of outstanding shares — as of September 30, 2025.
A total of 149 institutional investors currently hold OMER stock, with a combined institutional value of approximately $134,721,690 as of the most recent 13F filing period.
Frequently asked questions
OMER ownershipOmeros Corporation (OMER) is primarily owned by institutional investors, who hold approximately 45.4% of shares. The largest shareholder is BLACKROCK, INC. with a 7.60% stake. Company insiders hold 3.58%. Data sourced from SEC Form 13F as of September 30, 2025.