ROSENTHAL ARNON (Chief Executive Officer) received a stock award from ALECTOR, INC.

Compensation award — not an open‑market transaction. Less informative as a directional signal.

A · 1 award

ROSENTHAL ARNON

Filed: 10/15/2026ACC: 0001193125-26-422869

InsiderROSENTHAL ARNONCIK 1757770

→

IssuerALECTOR, INC.CIK 1653087

DirectorOfficer· Chief Executive Officer

Since Feb 2019

+1.20M

Net shares

Net buyer

$0.00

Total acquired

Open market trades

0B · 0S

Total transactions

3.62M acquired · 2.42M disposed

Non-Derivative Transactions1

Common Stock

Direct

A · Award

+217.50K

Price / share

—

Trade value

—

% of position

9.5%

10/14/2026

2.29M→2.51M

Total

Net shares

+217.50K

Net value

$0.00

Security	Date	Type	Shares	Price / Share	Trade Value	% of Position	Held Before	Held After
Common Stock Direct	10/14/2026	A · Award	+217.50K	—	—	9.5%	2.29M	2.51M
Total			+217.50K		$0.00

Derivative Transactions15

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

500K shares

−500K

Strike price

8.16

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

500K shares

+500K

Strike price

1.87

Held after

500K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

275K shares

−275K

Strike price

10.14

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

275K shares

+275K

Strike price

1.87

Held after

275K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

520K shares

−520K

Strike price

17.15

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

520K shares

+520K

Strike price

1.87

Held after

520K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

457.04K shares

−457.04K

Strike price

10.24

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

457.04K shares

+457.04K

Strike price

1.87

Held after

457.04K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

417.21K shares

−417.21K

Strike price

23.70

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

417.21K shares

+417.21K

Strike price

1.87

Held after

417.21K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

119.45K shares

−119.45K

Strike price

9.46

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

119.45K shares

+119.45K

Strike price

1.87

Held after

119.45K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

132.50K shares

−132.50K

Strike price

6.48

Held after

0.00

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

132.50K shares

+132.50K

Strike price

1.87

Held after

132.50K

Exercisable

—

10/13/2026

Employee Stock Option (right to buy)

Direct

A · Award

Converts to

Common Stock

978.75K shares

+978.75K

Strike price

1.88

Held after

978.75K

Exercisable

—

10/14/2026

Security	Converts To	Date	Type	Shares	Strike Price	Exercisable	Held After
Employee Stock Option (right to buy) Direct	Common Stock500K shares	10/13/2026	D · Disposition	−500K	8.16	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock500K shares	10/13/2026	A · Award	+500K	1.87	—	500K
Employee Stock Option (right to buy) Direct	Common Stock275K shares	10/13/2026	D · Disposition	−275K	10.14	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock275K shares	10/13/2026	A · Award	+275K	1.87	—	275K
Employee Stock Option (right to buy) Direct	Common Stock520K shares	10/13/2026	D · Disposition	−520K	17.15	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock520K shares	10/13/2026	A · Award	+520K	1.87	—	520K
Employee Stock Option (right to buy) Direct	Common Stock457.04K shares	10/13/2026	D · Disposition	−457.04K	10.24	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock457.04K shares	10/13/2026	A · Award	+457.04K	1.87	—	457.04K
Employee Stock Option (right to buy) Direct	Common Stock417.21K shares	10/13/2026	D · Disposition	−417.21K	23.70	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock417.21K shares	10/13/2026	A · Award	+417.21K	1.87	—	417.21K
Employee Stock Option (right to buy) Direct	Common Stock119.45K shares	10/13/2026	D · Disposition	−119.45K	9.46	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock119.45K shares	10/13/2026	A · Award	+119.45K	1.87	—	119.45K
Employee Stock Option (right to buy) Direct	Common Stock132.50K shares	10/13/2026	D · Disposition	−132.50K	6.48	—	0.00
Employee Stock Option (right to buy) Direct	Common Stock132.50K shares	10/13/2026	A · Award	+132.50K	1.87	—	132.50K
Employee Stock Option (right to buy) Direct	Common Stock978.75K shares	10/14/2026	A · Award	+978.75K	1.88	—	978.75K

Non-Derivative Holdings (Post-Transaction)4

Common Stock

Indirect

Shares owned1M

Common Stock

Indirect

Shares owned1M

Common Stock

Indirect

Shares owned1M

Common Stock

Indirect

Shares owned922.88K

Total

3.93M indirect3.93M

Security Title	Shares Owned	Ownership Type
Common Stock	1M	Indirect
Common Stock	1M	Indirect
Common Stock	1M	Indirect
Common Stock	922.88K	Indirect
Total	3.93M	3.93M indirect

Derivative Holdings (Post-Transaction)0

No derivative holdings reported