Institutional HoldersBeta

Who holds a company, from every 13F filed for the quarter, one row per filer exactly as filed, against the latest share count the company reported.

Alector, Inc.

CIK 0001653087ALEC· quarter ending 2026-06-30

Shares outstanding

111,656,919

as of 2026-07-31 · 10-Q cover page, filed 2026-08-06

Held by 13F filers

95,850,432

85.8% of shares outstanding

Holders

140

+2 vs 2026-03-31 · 13 new, 11 exited

Value

$192.7M

shares +8.4% vs prior quarter

Share classes (cover page of the 10-Q filed 2026-08-06, as of 2026-07-31)

Class	Listed	Shares outstanding	Held by 13F filers	% of class	Holders	CUSIP
Common stock	ALEC · NASDAQ	111,656,919	95,850,432	85.8%	140	014442107

Each class is compared with its own share count; classes are not added together. A class that is not exchange-listed cannot be held by 13F filers.

Securities (CUSIPs held in 13F this quarter)

tick to combine

Count	CUSIP	Class (as filers write it)	Holders	Shares held	Class shares	% of class	Value	Options	Mapped via
	014442107	COM	140	95,850,432	111,656,919	85.8%	$192.7M	3 call / 2 put	13DG	holders →

Totals combine the ticked CUSIPs and update as you tick: common-stock classes by default; preferreds, notes, warrants and depositary shares are listed but not counted. "holders →" shows a single CUSIP on its own. Bonds are held as a principal amount, not shares. Options positions are never counted as holdings.

Top holders (140 of 140 · 014442107)

change vs 2026-03-31

#	Filer	Shares	% of class	Value	Change
1	TCG Crossover Management, LLC	10,000,000	8.96%	$20.1M	—
2	Nantahala Capital Management, LLC	8,636,218	7.73%	$17.4M	+5,820,235 (+206.7%)
3	BlackRock, Inc.	7,847,879	7.03%	$15.8M	+106,634 (+1.4%)
4	ACADIAN ASSET MANAGEMENT LLC	4,414,345	3.95%	$8.9M	+375,560 (+9.3%)
5	VANGUARD CAPITAL MANAGEMENT LLC	4,009,340	3.59%	$8.1M	+330,618 (+9.0%)
6	Kynam Capital Management, LP	3,808,494	3.41%	$7.7M	+1,808,494 (+90.4%)
7	Merck & Co., Inc.	3,545,719	3.18%	$7.1M	—
8	Balyasny Asset Management L.P.	3,247,426	2.91%	$6.5M	+312,173 (+10.6%)
9	683 Capital Management, LLC	3,200,000	2.87%	$6.4M	—
10	D. E. Shaw & Co., Inc.	2,959,983	2.65%	$5.9M	-372,852 (-11.2%)
11	ADAR1 Capital Management, LLC	2,883,583	2.58%	$5.8M	+1,833,583 (+174.6%)
12	VANGUARD PORTFOLIO MANAGEMENT LLC	2,820,493	2.53%	$5.7M	+236,951 (+9.2%)
13	GEODE CAPITAL MANAGEMENT, LLC	2,454,271	2.20%	$4.9M	+168,053 (+7.4%)
14	Spruce Street Capital LP	2,101,068	1.88%	$4.2M	—
15	MILLENNIUM MANAGEMENT LLC	1,988,835	1.78%	$4.0M	+9,609 (+0.5%)
16	Ikarian Capital, LLC	1,982,606	1.78%	$4.0M	-100,000 (-4.8%)
17	STATE STREET CORP	1,879,765	1.68%	$3.8M	+14,239 (+0.8%)
18	JACOBS LEVY EQUITY MANAGEMENT, INC	1,765,929	1.58%	$3.5M	-388,432 (-18.0%)
19	MEDICI CAPITAL LLC	1,652,520	1.48%	$3.3M	—
20	Affinity Asset Advisors, LLC	1,510,000	1.35%	$3.0M	+1,010,000 (+202.0%)
21	Eversept Partners, LP	1,423,873	1.28%	$2.9M	+72,767 (+5.4%)
22	FMR LLC	1,396,398	1.25%	$2.8M	-399,706 (-22.3%)
23	AQR CAPITAL MANAGEMENT LLC	1,309,577	1.17%	$2.6M	+598,243 (+84.1%)
24	Euclidean Capital LLC	1,307,858	1.17%	$2.6M	—
25	MACKENZIE FINANCIAL CORP	1,109,770	0.99%	$2.2M	+252,416 (+29.4%)
26	DEUTSCHE BANK AG\	1,098,388	0.98%	$2.2M	+5,485 (+0.5%)
27	DEERFIELD MANAGEMENT COMPANY, L.P.	1,055,192	0.95%	$2.1M	—
28	TWO SIGMA INVESTMENTS, LP	1,045,376	0.94%	$2.1M	-233,930 (-18.3%)
29	RENAISSANCE TECHNOLOGIES LLC	935,166	0.84%	$1.9M	-352,525 (-27.4%)
30	DAFNA Capital Management LLC	908,351	0.81%	$1.8M	—
31	Elmind Capital, LP	900,000	0.81%	$1.8M	—
32	PANAGORA ASSET MANAGEMENT INC	845,999	0.76%	$1.7M	+255,611 (+43.3%)
33	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	818,831	0.73%	$1.6M	+31,423 (+4.0%)
34	NORTHERN TRUST CORP	773,462	0.69%	$1.6M	+81,206 (+11.7%)
35	VANGUARD FIDUCIARY TRUST CO	663,592	0.59%	$1.3M	+85,653 (+14.8%)
36	MARSHALL WACE, LLP	598,559	0.54%	$1.2M	-21,865 (-3.5%)
37	CANTOR FITZGERALD, L. P.	590,984	0.53%	$1.2M	NEW
38	BOOTHBAY FUND MANAGEMENT, LLC	532,850	0.48%	$1.1M	-26,876 (-4.8%)
39	GOLDMAN SACHS GROUP INC	433,875	0.39%	$872K	-170,687 (-28.2%)
40	XTX Topco Ltd	399,681	0.36%	$803K	-160,215 (-28.6%)
41	CITADEL ADVISORS LLC	391,232	0.35%	$786K	+313,687 (+404.5%)
42	UBS Group AG	273,780	0.25%	$550K	+128,436 (+88.4%)
43	Invesco Ltd.	257,139	0.23%	$517K	-7,928 (-3.0%)
44	Bank of New York Mellon Corp	250,093	0.22%	$503K	-2,204 (-0.9%)
45	AMERIPRISE FINANCIAL INC	224,530	0.20%	$451K	-46,742 (-17.2%)
46	NANO CAP NEW MILLENNIUM GROWTH FUND L P	200,000	0.18%	$402K	—
47	LMR Partners LLP	200,000	0.18%	$402K	NEW
48	Nuveen, LLC	176,234	0.16%	$354K	+21,304 (+13.8%)
49	Utah Retirement Systems	154,290	0.14%	$310K	—
50	BANK OF AMERICA CORP /DE/	142,678	0.13%	$287K	-238,230 (-62.5%)
51	BRIDGEWAY CAPITAL MANAGEMENT, LLC	142,500	0.13%	$286K	—
52	CANADA PENSION PLAN INVESTMENT BOARD	131,300	0.12%	$264K	-51,900 (-28.3%)
53	MORGAN STANLEY	120,480	0.11%	$242K	-244,087 (-67.0%)
54	PUBLIC EMPLOYEES RETIREMENT SYSTEM OF OHIO	119,769	0.11%	$241K	-16,231 (-11.9%)
55	RHUMBLINE ADVISERS	109,532	0.10%	$220K	+8,205 (+8.1%)
56	ALLIANCEBERNSTEIN L.P.	108,940	0.10%	$234K	+16,000 (+17.2%)
57	STRS OHIO	101,600	0.09%	$204K	+15,100 (+17.5%)
58	Russell Investments Group, Ltd.	98,496	0.09%	$198K	+32,365 (+48.9%)
59	WELLS FARGO & COMPANY/MN	89,172	0.08%	$179K	+54,646 (+158.3%)
60	SIMPLEX TRADING, LLC	85,488	0.08%	$172K	+17,011 (+24.8%)
61	PRICE T ROWE ASSOCIATES INC /MD/	81,655	0.07%	$165K	+25,555 (+45.6%)
62	Blackstone Inc.	77,145	0.07%	$155K	—
63	Jasper Ridge Partners, L.P.	73,531	0.07%	$148K	—
64	SEI INVESTMENTS CO	71,151	0.06%	$143K	+17,305 (+32.1%)
65	DZ BANK AG Deutsche Zentral Genossenschafts Bank, Frankfurt am Main	69,666	0.06%	$140K	—
66	IEQ CAPITAL, LLC	60,570	0.05%	$122K	+13,490 (+28.7%)
67	Verdad Advisers, LP	60,509	0.05%	$122K	+36,955 (+156.9%)
68	MetLife Investment Management, LLC	58,696	0.05%	$118K	+22,488 (+62.1%)
69	Mariner, LLC	52,709	0.05%	$106K	+33,910 (+180.4%)
70	Vanguard Personalized Indexing Management, LLC	49,445	0.04%	$99K	-1,184 (-2.3%)
71	HSBC HOLDINGS PLC	48,523	0.04%	$98K	—
72	Graham Capital Management, L.P.	46,496	0.04%	$93K	NEW
73	CITIGROUP INC	46,275	0.04%	$93K	+41,636 (+897.5%)
74	MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd.	45,190	0.04%	$91K	+2,529 (+5.9%)
75	BARCLAYS PLC	44,957	0.04%	$90K	+2,366 (+5.6%)
76	JPMORGAN CHASE & CO	42,998	0.04%	$89K	+5,619 (+15.0%)
77	DIVERSIFIED TRUST CO	42,351	0.04%	$85K	+16,456 (+63.5%)
78	DIMENSIONAL FUND ADVISORS LP	33,728	0.03%	$68K	-250,089 (-88.1%)
79	Cerity Partners LLC	32,521	0.03%	$65K	+5,545 (+20.6%)
80	Vanguard Global Advisers, LLC	31,302	0.03%	$63K	—
81	Cannell & Spears LLC	30,342	0.03%	$61K	-24,300 (-44.5%)
82	WEALTH ENHANCEMENT ADVISORY SERVICES, LLC	30,251	0.03%	$49K	+12,054 (+66.2%)
83	Vontobel Holding Ltd.	30,000	0.03%	$60K	—
84	Point72 Asset Management, L.P.	26,699	0.02%	$54K	-53,392 (-66.7%)
85	ROYAL BANK OF CANADA	26,122	0.02%	$53K	+19,075 (+270.7%)
86	MERCER GLOBAL ADVISORS INC /ADV	25,504	0.02%	$51K	NEW
87	GROUP ONE TRADING LLC	25,208	0.02%	$51K	NEW
88	INTECH INVESTMENT MANAGEMENT LLC	24,530	0.02%	$49K	+576 (+2.4%)
89	SUSQUEHANNA INTERNATIONAL GROUP, LLP	24,123	0.02%	$48K	-83,474 (-77.6%)
90	Police & Firemen's Retirement System of New Jersey	23,426	0.02%	$47K	—
91	VOYA INVESTMENT MANAGEMENT LLC	21,898	0.02%	$44K	+6,420 (+41.5%)
92	BNP PARIBAS FINANCIAL MARKETS	21,200	0.02%	$43K	+1,173 (+5.9%)
93	MANUFACTURERS LIFE INSURANCE COMPANY, THE	19,397	0.02%	$39K	-6,751 (-25.8%)
94	Qube Research & Technologies Ltd	16,569	0.01%	$33K	NEW
95	CAPTRUST FINANCIAL ADVISORS	16,037	0.01%	$32K	+5,389 (+50.6%)
96	PRUDENTIAL FINANCIAL INC	16,015	0.01%	$32K	-7,780 (-32.7%)
97	Creative Planning	15,015	0.01%	$30K	NEW
98	Tower Research Capital LLC (TRC)	14,450	0.01%	$29K	+8,507 (+143.1%)
99	HAMILTON LANE ADVISORS LLC	14,400	0.01%	$29K	—
100	Quadrature Capital Ltd	14,169	0.01%	$28K	-5,317 (-27.3%)
101	NEUBERGER BERMAN GROUP LLC	13,521	0.01%	$27K	-1,007 (-6.9%)
102	ProShare Advisors LLC	12,848	0.01%	$26K	-340 (-2.6%)
103	Bronte Capital Management Pty Ltd.	11,758	0.01%	$24K	-7,524 (-39.0%)
104	Merit Financial Group, LLC	11,243	0.01%	$23K	+315 (+2.9%)
105	NEW YORK STATE COMMON RETIREMENT FUND	10,310	0.01%	$21K	—
106	HighTower Advisors, LLC	10,227	0.01%	$21K	-533 (-5.0%)
107	Legal & General Group Plc	8,346	0.01%	$17K	—
108	Ameritas Investment Partners, Inc.	8,175	0.01%	$16K	—
109	Arax Advisory Partners	5,433	0.00%	$11K	+5,254 (+2935.2%)
110	China Universal Asset Management Co., Ltd.	3,600	0.00%	$7K	NEW
111	Allworth Financial LP	2,479	0.00%	$5K	+1,852 (+295.4%)
112	GAMMA Investing LLC	1,523	0.00%	$3K	—
113	NISA INVESTMENT ADVISORS, LLC	1,416	0.00%	$3K	+400 (+39.4%)
114	EverSource Wealth Advisors, LLC	1,309	0.00%	$3K	+422 (+47.6%)
115	CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM	1,274	0.00%	$3K	-3,620 (-74.0%)
116	Essential Partners LLC	1,237	0.00%	$2K	-2,620 (-67.9%)
117	Optiver Holding B.V.	925	0.00%	$2K	-776 (-45.6%)
118	True Wealth Design, LLC	867	0.00%	$2K	+274 (+46.2%)
119	Physician Wealth Advisors, Inc.	752	0.00%	$2K	—
120	ROTHSCHILD INVESTMENT LLC	680	0.00%	$1K	+440 (+183.3%)
121	Sterling Capital Management LLC	523	0.00%	$1K	-2,283 (-81.4%)
122	Basecamp Wealth Advisors LLC	446	0.00%	$896	+117 (+35.6%)
123	Federation des caisses Desjardins du Quebec	415	0.00%	$834	—
124	Wilmington Savings Fund Society, FSB	400	0.00%	$804	—
125	Hughes Financial Services, LLC	388	0.00%	$780	-24 (-5.8%)
126	Rockefeller Capital Management L.P.	367	0.00%	$738	—
127	OSAIC HOLDINGS, INC.	300	0.00%	$603	NEW
128	MARK SHEPTOFF FINANCIAL PLANNING, LLC	300	0.00%	$603	—
129	Farther Finance Advisors, LLC	253	0.00%	$509	+97 (+62.2%)
130	NATIONAL BANK OF CANADA /FI/	200	0.00%	$400	—
131	Fortitude Family Office, LLC	134	0.00%	$269	-121 (-47.5%)
132	Clearstead Advisors, LLC	125	0.00%	$252	NEW
133	Wealth Enhancement Trust Services, Inc.	105	0.00%	$211	NEW
134	IFP Advisors, Inc	94	0.00%	$189	+88 (+1466.7%)
135	Kingdom Financial Group LLC.	48	0.00%	$96	—
136	SJS Investment Consulting Inc.	43	0.00%	$87	NEW
137	Caitong International Asset Management Co., Ltd	42	0.00%	$84	+40 (+2000.0%)
138	SBI Securities Co., Ltd.	20	0.00%	$40	—
139	JPL Wealth Management, LLC	18	0.00%	$37	NEW
140	FIFTH THIRD BANCORP	6	0.00%	$12	—

Exited since 2026-03-31 (11 filers; largest 11 shown)

Foresite Capital Management IV, LLC	−3,887,200
JANE STREET GROUP, LLC	−399,464
Odyssean, LLC	−89,783
GSA CAPITAL PARTNERS LLP	−78,207
CWM, LLC	−28,985
State of Wyoming	−1,645
Root Financial Partners, LLC	−305
Advisory Services Network, LLC	−271
MAI Capital Management	−67
Lloyd Advisory Services, LLC.	−48
Sunbelt Securities, Inc.	−17

Large holders from 13D/13G (latest per reporting person, last 2 years)

Filed when a holder crosses 5% or changes materially, so often more current than the quarter-end 13F. Percentages are the filer's own, against the share count they used.

Reporting person	Form	Filed	Event	Shares	% of class
BVF I GP LLC	SCHEDULE 13G	2026-09-18	2026-09-11	4,900,143	4.4%
LAMPERT MARK N	SCHEDULE 13G	2026-09-18	2026-09-11	9,374,267	8.4%
BVF Partners OS Ltd.	SCHEDULE 13G	2026-09-18	2026-09-11	619,317	0.6%
BIOTECHNOLOGY VALUE FUND II LP	SCHEDULE 13G	2026-09-18	2026-09-11	3,671,016	3.3%
BIOTECHNOLOGY VALUE FUND L P	SCHEDULE 13G	2026-09-18	2026-09-11	4,900,143	4.4%
Biotechnology Value Trading Fund OS LP	SCHEDULE 13G	2026-09-18	2026-09-11	619,317	0.6%
BVF PARTNERS L P/IL	SCHEDULE 13G	2026-09-18	2026-09-11	9,374,267	8.4%
BVF INC/IL	SCHEDULE 13G	2026-09-18	2026-09-11	9,374,267	8.4%
BVF II GP LLC	SCHEDULE 13G	2026-09-18	2026-09-11	3,671,016	3.3%
BVF GP HOLDINGS LLC	SCHEDULE 13G	2026-09-18	2026-09-11	8,571,159	7.7%
Jonathan A. Flint	SCHEDULE 13G/A	2026-05-14	2026-03-31	4,892,941	4.4%
Polaris Venture Partners VI (AIV-B), L.P.	SCHEDULE 13G/A	2026-05-14	2026-03-31	806,528	0.7%
Brian Chee	SCHEDULE 13G/A	2026-05-14	2026-03-31	4,853,817	4.4%
Terrance G. McGuire	SCHEDULE 13G/A	2026-05-14	2026-03-31	5,173,499	4.7%
David Barrett	SCHEDULE 13G/A	2026-05-14	2026-03-31	4,853,817	4.4%
Bryce Youngren	SCHEDULE 13G/A	2026-05-14	2026-03-31	4,865,681	4.4%
Polaris Venture Partners VI, L.P.	SCHEDULE 13G/A	2026-05-14	2026-03-31	498,468	0.5%
Amir Nashat	SCHEDULE 13G/A	2026-05-14	2026-03-31	4,985,149	4.5%
Polaris Venture Partners VI (AIV), L.P.	SCHEDULE 13G/A	2026-05-14	2026-03-31	3,280,842	3%
Polaris Venture Management Co VI, L.L.C.	SCHEDULE 13G/A	2026-05-14	2026-03-31	4,853,817	4.4%
Polaris Venture Partners Founders' Fund VI, L.P.	SCHEDULE 13G/A	2026-05-14	2026-03-31	267,979	0.2%
BlackRock, Inc.	SCHEDULE 13G	2026-04-27	2026-03-31	5,784,214	5.2%
The Vanguard Group	SCHEDULE 13G/A	2026-03-26	2026-03-13	0	0%
Roderick Wong	SCHEDULE 13G/A	2026-02-17	2025-12-31	0	0%
RTW Investments, LP	SCHEDULE 13G/A	2026-02-17	2025-12-31	0	0%
Arnon Rosenthal	SCHEDULE 13G/A	2026-02-06	2025-12-31	8,213,925	7.4%
TCG Crossover GP III, LLC	SCHEDULE 13G	2025-11-14	2025-10-22	5,000,000	4.6%
TCG Crossover Fund III, L.P.	SCHEDULE 13G	2025-11-14	2025-10-22	5,000,000	4.6%
TCG Crossover Fund II, L.P.	SCHEDULE 13G	2025-11-14	2025-10-22	5,000,000	4.6%
TCG Crossover GP II, LLC	SCHEDULE 13G	2025-11-14	2025-10-22	5,000,000	4.6%
Chen Yu	SCHEDULE 13G	2025-11-14	2025-10-22	10,000,000	9.2%
FMR LLC	SCHEDULE 13G/A	2025-11-07	2025-10-31	3,599,820	3.6%
Abigail P. Johnson	SCHEDULE 13G/A	2025-11-07	2025-10-31	3,599,820	3.6%
RA Capital Management, L.P.	SCHEDULE 13G/A	2025-08-14	2025-06-30	0	0%
Rajeev Shah	SCHEDULE 13G/A	2025-08-14	2025-06-30	0	0%
RA Capital Healthcare Fund, L.P.	SCHEDULE 13G/A	2025-08-14	2025-06-30	0	0%
Peter Kolchinsky	SCHEDULE 13G/A	2025-08-14	2025-06-30	0	0%

Source: SEC Form 13F-HR information tables for the quarter ending 2026-06-30 (filed within 45 days of quarter end; amendments applied; values normalised to dollars), the share count from the company's latest 10-K/10-Q XBRL cover page, and Schedule 13D/13G filings. Each row is a legal 13F filer as filed — related entities (e.g. Vanguard's advisers) are not merged. Retail brokerage accounts are not reported on 13F, so the remainder is mostly retail and insiders.