Alector ALEC Insider Ownership

NASDAQ ALEC

$1.87 -0.10 (-5.08%)

At close: Oct 21, 2026 · 4:00 PM EDT

Insider Holdings by Owner

29.02Mn Shares

Insider Ownership Statistics

as of 30 Sep, 2026

Insider Ownership

7.73%

▼-0.082% pp QoQ

Shares Held by Insiders

8.63Mn

filed for Sep 2026

▼-1.05% QoQ

Shares Outstanding

111.66Mn

111,656,805 shares

Direct Holdings

4.69Mn

Indirect: 3.94Mn

Net Shares Traded (QoQ)

-91.30K

net selling in Sep 2026

Insiders Holding Shares

with Form 4 holdings on file

Shares Owned by Insiders

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Shares Purchased/Sold by Insiders

Bought Sold

Latest quarter —

Net over range —

Buying quarters —

Insider Ownership Summary

Updated Oct 16, 2026

In the last 12 months, insiders at Alector made open-market sales of $1.02 million (553.02K shares) and bought no shares on the open market.

Counted by insider, open-market selling of ALEC stock in the past 12 months came from 4 insiders, with no insider buying.
Arnon Rosenthal (Chief Executive Officer) led open-market sales of Alector stock over the past 12 months with $656,312 (346.03K shares), most recently on September 3, 2026.
Alector's latest insider trade on the open market was a sale of 3.62K shares for $9,094 by Grace Wong-Sarad (Principal Accounting Officer) on September 4, 2026.
Apart from open-market trades, ALEC insiders received 819.51K shares in stock awards and gave away 1.05Mn shares as gifts in the past 12 months.
Per Business Quant, ALEC insiders together hold 8.95Mn shares based on their latest Form 4 filings, up 2.60% from 8.72Mn shares at the end of Q2 2026.
Alector insiders hold 5.01Mn shares directly (55.95% of their total) and 3.94Mn shares (44.05%) indirectly, through entities such as trusts and partnerships.
Per Business Quant, 13 insiders of ALEC hold shares, counting officers, directors and 10% owners who have filed a Form 4 in the past two years.
ALEC's largest insider holders by reported holdings are Arnon Rosenthal (Chief Executive Officer, 6.44Mn shares), Sara Kenkare-Mitra (President and Head of R&D, 501.65K shares) and Neil Lindsay Berkley (CFO & Chief Business Officer, 395.22K shares).
The holding of Arnon Rosenthal makes up 72.01% of all shares held by Alector insiders.
Institutional investors held 81.68% of Alector stock at the end of Q2 2026, while the latest Form 4 filings of its insiders account for about 8.01%; other investors, including the public, hold roughly 10.31%.
A total of 36 Form 4 filings with transactions in Alector stock were made over the past 12 months, by 11 insiders.
The insider data for ALEC reflects Form 4 filings through October 15, 2026.

Form 4 Holdings

Insiders Holding ALEC

Insiders 18

Shares held 29.02Mn

Of outstanding 25.99%

#	Insider	Position	Direct	Indirect	Total	Share of Insiders	Last Filed
1	Terrance Mcguire	Director, TenPercentOwner	0	10,853,817	10,853,817	37.4%	13 Sep, 2023
2	Venture Management Co. Vi, L.L.C. Polaris	TenPercentOwner	0	9,853,817	9,853,817	34.0%	31 May, 2024
3	Tillman U. Gerngross	Director	2,644,319	0	2,644,319	9.1%	15 Jun, 2023
4	Arnon Rosenthal	Chief Executive Officer	2,512,100	0	2,512,100	8.7%	15 Oct, 2026
5	Robert King	Chief Development Officer	550,871	0	550,871	1.9%	04 Oct, 2022
6	Sara Kenkare-Mitra	President And Head Of Rd	501,652	0	501,652	1.7%	03 Dec, 2025
7	Neil Lindsay Berkley	Cfo Chief Business Officer	395,216	0	395,216	1.4%	15 Oct, 2026
8	Gary Romano	Chief Medical Officer	332,977	0	332,977	1.1%	05 Mar, 2025
9	Marc Grasso	Chief Financial Officer	296,072	0	296,072	1.0%	04 Jun, 2025
10	Grace Wong-Sarad	Principal Accounting Officer	161,570	0	161,570	0.6%	15 Oct, 2026
11	Richard H Scheller	Director	134,899	0	134,899	0.5%	17 Jun, 2026
12	Louis J Jr Lavigne	Director	128,109	0	128,109	0.4%	17 Jun, 2026
13	Kristine Yaffe	Director	124,109	0	124,109	0.4%	17 Jun, 2026
14	Elizabeth A. Garofalo	Director	118,650	0	118,650	0.4%	17 Jun, 2026
15	David M. Wehner	Director	115,330	0	115,330	0.4%	12 Jun, 2024
16	Paula Hammond	Director	103,609	0	103,609	0.4%	17 Jun, 2026
17	Errol B Desouza	Director	98,650	0	98,650	0.3%	17 Jun, 2026
18	Mark Altmeyer	Director	98,650	0	98,650	0.3%	17 Jun, 2026

Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.

Form 4 Filings

684 Insider Transactions

Source SEC Form 4

Latest quarter Sep 2026

Date	Insider	Position	Transaction	Shares	Price	Value	Shares Held After	Ownership
14 Oct, 2026	Neil Lindsay Berkley	Cfo Chief Business Officer	Acquired A	44,567	$0.00	$0	395,216	Direct
14 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Acquired A	217,500	$0.00	$0	2,512,100	Direct
14 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Acquired A	55,555	$0.00	$0	161,570	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Disposed D	20,000	—	—	0	Direct
14 Oct, 2026	Neil Lindsay Berkley	Cfo Chief Business Officer	Acquired A	190,000	$0.00	$0	190,000	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Acquired A	20,000	—	—	20,000	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Disposed D	13,842	—	—	0	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Acquired A	13,842	—	—	13,842	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Disposed D	20,454	—	—	0	Direct
13 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Disposed D	500,000	—	—	0	Direct
13 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Acquired A	500,000	—	—	500,000	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Acquired A	20,454	—	—	20,454	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Disposed D	10,228	—	—	0	Direct
13 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Disposed D	275,000	—	—	0	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Acquired A	10,228	—	—	10,228	Direct
13 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Acquired A	275,000	—	—	275,000	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Disposed D	11,552	—	—	0	Direct
13 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Disposed D	520,000	—	—	0	Direct
13 Oct, 2026	Arnon Rosenthal	Chief Executive Officer	Acquired A	520,000	—	—	520,000	Direct
13 Oct, 2026	Grace Wong-Sarad	Principal Accounting Officer	Acquired A	11,552	—	—	11,552	Direct

Showing 1 to 20 of 684 transactions