ALECTOR INC ALEC
COM · Common Stock · CUSIP 014442107 · ISIN US0144421072
Company in San Francisco, United States
- SectorHealth care
- IndustryBiological Products, (No Diagnostic Substances)
- HeadquartersSouth San Francisco, CA
- Founded2013
- Websitealector.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($100.0k this quarter). Holder counts are more reliable. Shares outstanding: 111.7m as of 2026-07-31, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $2.01. Options: 5 managers hold calls ($1.6m notional), 3 hold puts ($262.7k).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 168 |
| Q4 2022 | 155 |
| Q1 2023 | 150 |
| Q2 2023 | 146 |
| Q3 2023 | 150 |
| Q4 2023 | 149 |
| Q1 2024 | 158 |
| Q2 2024 | 161 |
| Q3 2024 | 160 |
| Q4 2024 | 151 |
| Q1 2025 | 142 |
| Q2 2025 | 137 |
| Q3 2025 | 149 |
| Q4 2025 | 131 |
| Q1 2026 | 138 |
| Q2 2026 | 141 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 64 | 69 |
| Q4 2024 | 67 | 77 |
| Q1 2025 | 65 | 58 |
| Q2 2025 | 63 | 60 |
| Q3 2025 | 70 | 53 |
| Q4 2025 | 61 | 79 |
| Q1 2026 | 68 | 56 |
| Q2 2026 | 73 | 44 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $1.9m | $807.5k | 0.42 |
| Q4 2025 | $863.5k | $269.1k | 0.31 |
| Q1 2026 | $669.5k | $21.5k | 0.03 |
| Q2 2026 | $1.6m | $262.7k | 0.17 |
Biggest buyers
| Nantahala Capital Management, LLC | Added | +5.8m |
| ADAR1 Capital Management, LLC | Added | +1.8m |
| Kynam Capital Management, LP | Added | +1.8m |
| Affinity Asset Advisors, LLC | Added | +1.0m |
| AQR CAPITAL MANAGEMENT LLC | Added | +598.2k |
| CANTOR FITZGERALD, L. P. | New | +591.0k |
| ACADIAN ASSET MANAGEMENT LLC | Added | +375.6k |
| VANGUARD CAPITAL MANAGEMENT LLC | Added | +330.6k |
| CITADEL ADVISORS LLC | Added | +313.7k |
| Balyasny Asset Management L.P. | Added | +312.2k |
Biggest sellers
| Foresite Capital Management IV, LLC | Sold out | -3.9m |
| FMR LLC | Reduced | -399.7k |
| JANE STREET GROUP, LLC | Sold out | -399.5k |
| JACOBS LEVY EQUITY MANAGEMENT, INC | Reduced | -388.4k |
| D. E. Shaw & Co., Inc. | Reduced | -372.9k |
| RENAISSANCE TECHNOLOGIES LLC | Reduced | -352.5k |
| DIMENSIONAL FUND ADVISORS LP | Reduced | -250.1k |
| MORGAN STANLEY | Reduced | -244.1k |
| BANK OF AMERICA CORP /DE/ | Reduced | -238.2k |
| TWO SIGMA INVESTMENTS, LP | Reduced | -233.9k |
Biggest calls
| Balyasny Asset Management L.P. | New | $1.0m503.9k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $273.2k135.9k shares |
| JANE STREET GROUP, LLC | Added | $241.4k120.1k shares |
| SIMPLEX TRADING, LLC | Reduced | $43.2k21.5k shares |
| GROUP ONE TRADING LLC | Reduced | $1.0k500 shares |
Biggest puts
| CITADEL ADVISORS LLC | New | $218.9k108.9k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | New | $24.9k12.4k shares |
| SIMPLEX TRADING, LLC | Reduced | $18.9k9.4k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| TCG Crossover GP II, LLC 13G · passive investor new · filed 2025-11-14 | 9.2% |
| Deep Track Capital, LP 13G · passive investor new · filed 2026-10-23 | 8.6% |
| BIOTECHNOLOGY VALUE FUND L P 13G · passive investor new · filed 2026-09-18 | 8.4% |
| Rosenthal Arnon 13G · exempt (held before listing) filed 2026-02-06 | 7.4% |
| BlackRock, Inc. 13G · institution +0.5 pts · filed 2026-04-27 | 5.2% |
| RA CAPITAL MANAGEMENT, L.P. 13G · passive investor +5.1 pts · filed 2026-10-26 | 5.1% |
Fell to 5% or below in the last year: Polaris Venture Partners VI, L.P. (4.7%, 2026-05-14), VANGUARD GROUP INC (0.0%, 2026-03-26), RTW INVESTMENTS, LP (0.0%, 2026-02-17)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 4 | $277.3k | — |
| Q1 2025 | 0 | — | 4 | $152.6k | — |
| Q2 2025 | 0 | — | 4 | $125.3k | $1.4k |
| Q3 2025 | 0 | — | 5 | $275.4k | $33.0k |
| Q4 2025 | 0 | — | 4 | $220.1k | — |
| Q1 2026 | 0 | — | 3 | $273.4k | $19.9k |
| Q2 2026 | 0 | — | 3 | $232.6k | $4.8k |
| Q3 2026 | 0 | — | 3 | $295.6k | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-09-04 | Wong-Sarad Grace Principal Accounting Officer | Sold | $9.1k3.6k shares |
| 2026-09-03 | Rosenthal Arnon Chief Executive Officer, director | Sold | $193.1k72.6k shares |
| 2026-09-03 | Berkley Neil Lindsay CFO & Chief Business Officer | Sold | $77.8k29.3k shares |
| 2026-09-03 | Wong-Sarad Grace Principal Accounting Officer | Sold | $13.8k5.2k shares |
| 2026-09-02 | Wong-Sarad Grace Principal Accounting Officer | Sold | $1.8k656 shares |
| 2026-06-03 | Wong-Sarad Grace Principal Accounting Officer | Sold | $6.5k3.5k shares |
| 2026-06-02 | Rosenthal Arnon Chief Executive Officer, director | Sold | $171.8k87.2k shares |
| 2026-06-02 | Berkley Neil Lindsay CFO & Chief Business Officer | Sold | $38.1k19.4k shares |
| 2026-06-02 | Wong-Sarad Grace Principal Accounting Officer | Sold | $11.2k5.7k shares |
| 2026-04-16 | Wong-Sarad Grace Principal Accounting Officer | Sold plan | $4.8k1.8k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| TCG Crossover Management, LLC 0.48% of their portfolio | 10.0m $20.1m | Unchanged |
| Nantahala Capital Management, LLC 0.53% of their portfolio | 8.6m $17.4m | Added +5.8m |
| BlackRock, Inc. 0.00% of their portfolio | 7.8m $15.8m | Added +106.6k |
| ACADIAN ASSET MANAGEMENT LLC 0.01% of their portfolio | 4.4m $8.9m | Added +375.6k |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 4.0m $8.1m | Added +330.6k |
| Kynam Capital Management, LP 0.42% of their portfolio | 3.8m $7.7m | Added +1.8m |
| Merck & Co., Inc. 1.35% of their portfolio | 3.5m $7.1m | Unchanged |
| Balyasny Asset Management L.P. 0.01% of their portfolio | 3.2m $6.5m | Added +312.2k |
| 683 Capital Management, LLC 0.59% of their portfolio | 3.2m $6.4m | Unchanged |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 3.0m $5.9m | Reduced -372.9k |
| ADAR1 Capital Management, LLC 0.27% of their portfolio | 2.9m $5.8m | Added +1.8m |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 2.8m $5.7m | Added +237.0k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 2.5m $4.9m | Added +168.1k |
| Spruce Street Capital LP 0.83% of their portfolio | 2.1m $4.2m | Unchanged |
| MILLENNIUM MANAGEMENT LLC 0.00% of their portfolio | 2.0m $4.0m | Added +9.6k |
| Ikarian Capital, LLC 0.65% of their portfolio | 2.0m $4.0m | Reduced -100.0k |
| STATE STREET CORP 0.00% of their portfolio | 1.9m $3.8m | Added +14.2k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.01% of their portfolio | 1.8m $3.5m | Reduced -388.4k |
| MEDICI CAPITAL LLC 6.51% of their portfolio | 1.7m $3.3m | Unchanged |
| Affinity Asset Advisors, LLC 0.15% of their portfolio | 1.5m $3.0m | Added +1.0m |
| Eversept Partners, LP 0.16% of their portfolio | 1.4m $2.9m | Added +72.8k |
| FMR LLC 0.00% of their portfolio | 1.4m $2.8m | Reduced -399.7k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 1.3m $2.6m | Added +598.2k |
| Euclidean Capital LLC 0.60% of their portfolio | 1.3m $2.6m | Unchanged |
| MACKENZIE FINANCIAL CORP 0.00% of their portfolio | 1.1m $2.2m | Added +252.4k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 1.1m $2.2m | Added +5.5k |
| DEERFIELD MANAGEMENT COMPANY, L.P. 0.02% of their portfolio | 1.1m $2.1m | Unchanged |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 1.0m $2.1m | Reduced -233.9k |
| RENAISSANCE TECHNOLOGIES LLC 0.00% of their portfolio | 935.2k $1.9m | Reduced -352.5k |
| DAFNA Capital Management LLC 0.35% of their portfolio | 908.4k $1.8m | Unchanged |
| Elmind Capital, LP 0.45% of their portfolio | 900.0k $1.8m | Unchanged |
| PANAGORA ASSET MANAGEMENT INC 0.01% of their portfolio | 846.0k $1.7m | Added +255.6k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 818.8k $1.6m | Added +31.4k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 773.5k $1.6m | Added +81.2k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 663.6k $1.3m | Added +85.7k |
| MARSHALL WACE, LLP 0.00% of their portfolio | 598.6k $1.2m | Reduced -21.9k |
| CANTOR FITZGERALD, L. P. 0.01% of their portfolio | 591.0k $1.2m | New |
| BOOTHBAY FUND MANAGEMENT, LLC 0.02% of their portfolio | 532.9k $1.1m | Reduced -26.9k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 433.9k $872.1k | Reduced -170.7k |
| XTX Topco Ltd 0.01% of their portfolio | 399.7k $803.4k | Reduced -160.2k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 391.2k $786.4k | Added +313.7k |
| UBS Group AG 0.00% of their portfolio | 273.8k $550.3k | Added +128.4k |
| Invesco Ltd. 0.00% of their portfolio | 257.1k $516.8k | Reduced -7.9k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 250.1k $502.7k | Reduced -2.2k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 224.5k $451.3k | Reduced -46.7k |
| NANO CAP NEW MILLENNIUM GROWTH FUND L P 0.31% of their portfolio | 200.0k $402.0k | Unchanged |
| LMR Partners LLP 0.00% of their portfolio | 200.0k $402.0k | New |
| Nuveen, LLC 0.00% of their portfolio | 176.2k $354.2k | Added +21.3k |
| Utah Retirement Systems 0.00% of their portfolio | 154.3k $310.1k | Unchanged |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 142.7k $286.8k | Reduced -238.2k |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.01% of their portfolio | 142.5k $286.4k | Unchanged |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 131.3k $263.9k | Reduced -51.9k |
| MORGAN STANLEY 0.00% of their portfolio | 120.5k $242.2k | Reduced -244.1k |
| PUBLIC EMPLOYEES RETIREMENT SYSTEM OF OHIO 0.00% of their portfolio | 119.8k $240.7k | Reduced -16.2k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 109.5k $220.1k | Added +8.2k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 108.9k $234.2k | Added +16.0k |
| STRS OHIO 0.00% of their portfolio | 101.6k $204.2k | Added +15.1k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 98.5k $198.0k | Added +32.4k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 89.2k $179.2k | Added +54.6k |
| SIMPLEX TRADING, LLC 0.00% of their portfolio | 85.5k $171.8k | Added +17.0k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 81.7k $165.0k | Added +25.6k |
| Blackstone Inc. 0.00% of their portfolio | 77.1k $155.1k | Unchanged |
| Jasper Ridge Partners, L.P. 0.00% of their portfolio | 73.5k $147.8k | Unchanged |
| SEI INVESTMENTS CO 0.00% of their portfolio | 71.2k $143.0k | Added +17.3k |
| DZ BANK AG Deutsche Zentral Genossenschafts Bank, Frankfurt am Main 0.00% of their portfolio | 69.7k $140.0k | Unchanged |
| IEQ CAPITAL, LLC 0.00% of their portfolio | 60.6k $121.7k | Added +13.5k |
| Verdad Advisers, LP 0.12% of their portfolio | 60.5k $121.6k | Added +37.0k |
| MetLife Investment Management, LLC 0.00% of their portfolio | 58.7k $118.0k | Added +22.5k |
| Mariner, LLC 0.00% of their portfolio | 52.7k $106.0k | Added +33.9k |
| Vanguard Personalized Indexing Management, LLC 0.00% of their portfolio | 49.4k $99.4k | Reduced -1.2k |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 48.5k $98.0k | Unchanged |
| Graham Capital Management, L.P. 0.00% of their portfolio | 46.5k $93.5k | New |
| CITIGROUP INC 0.00% of their portfolio | 46.3k $93.0k | Added +41.6k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 45.2k $90.8k | Added +2.5k |
| BARCLAYS PLC 0.00% of their portfolio | 45.0k $90.4k | Added +2.4k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 43.0k $89.4k | Added +5.6k |
| DIVERSIFIED TRUST CO 0.00% of their portfolio | 42.4k $85.1k | Added +16.5k |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 33.7k $68.0k | Reduced -250.1k |
| Cerity Partners LLC 0.00% of their portfolio | 32.5k $65.4k | Added +5.5k |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 31.3k $62.9k | Unchanged |
| Cannell & Spears LLC 0.00% of their portfolio | 30.3k $61.0k | Reduced -24.3k |
| WEALTH ENHANCEMENT ADVISORY SERVICES, LLC 0.00% of their portfolio | 30.3k $48.7k | Added +12.1k |
| Vontobel Holding Ltd. 0.00% of their portfolio | 30.0k $60.3k | Unchanged |
| Point72 Asset Management, L.P. 0.00% of their portfolio | 26.7k $53.7k | Reduced -53.4k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 26.1k $53.0k | Added +19.1k |
| MERCER GLOBAL ADVISORS INC /ADV 0.00% of their portfolio | 25.5k $51.3k | New |
| GROUP ONE TRADING LLC 0.00% of their portfolio | 25.2k $50.7k | New |
| INTECH INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 24.5k $49.3k | Added +576 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 24.1k $48.5k | Reduced -83.5k |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 23.4k $47.1k | Unchanged |
| VOYA INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 21.9k $44.0k | Added +6.4k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 21.2k $42.6k | Added +1.2k |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 19.4k $39.0k | Reduced -6.8k |
| Qube Research & Technologies Ltd 0.00% of their portfolio | 16.6k $33.3k | New |
| CAPTRUST FINANCIAL ADVISORS 0.00% of their portfolio | 16.0k $32.2k | Added +5.4k |
| PRUDENTIAL FINANCIAL INC 0.00% of their portfolio | 16.0k $32.2k | Reduced -7.8k |
| Creative Planning 0.00% of their portfolio | 15.0k $30.2k | New |
| Tower Research Capital LLC (TRC) 0.00% of their portfolio | 14.4k $29.0k | Added +8.5k |
| HAMILTON LANE ADVISORS LLC 0.02% of their portfolio | 14.4k $28.9k | Unchanged |
| Quadrature Capital Ltd 0.00% of their portfolio | 14.2k $28.5k | Reduced -5.3k |