ANNX Form 4: Director Satter reports new Annexon share purchases

Rhea-AI Filing Summary

Annexon, Inc. (ANNX) reported insider share purchases by director Muneer A. Satter through affiliated entities. On November 20, 2025, Alerce Medical Technology Partners, L.P. bought 400,000 shares of common stock at a weighted average price of $4.48. On November 21, 2025, Alerce Medical purchased an additional 422,613 shares at a weighted average price of $4.28. After these transactions, Satter is reported as beneficially owning 9,728,637 shares, held indirectly through a revocable trust, other trusts and entities, Satter Medical Technology Partners, L.P., and Alerce Medical, over which he has sole voting and dispositive power, while disclaiming beneficial ownership beyond his pecuniary interest.

Insights

Equity Ownership and Governance Analyst

Large director-led indirect share purchases increase aligned exposure through affiliated entities and trusts.

The filing reports that a director of Annexon, Inc. caused affiliated entities to purchase an aggregate of 822,613 shares of common stock on 11/20/2025 and 11/21/2025. The weighted average purchase prices were $4.48 and $4.28, across trade ranges disclosed in the footnotes. Following these purchases, the director’s indirectly held beneficial position, including various trusts and partnerships, totals 9,728,637 shares.

The structure is important. The shares were bought primarily by Alerce Medical Technology Partners, L.P. and other Satter-affiliated entities, over which the reporting person has sole voting and dispositive power. The footnotes clarify that the director disclaims beneficial ownership in several entities beyond his economic interest, which is common when managing capital for multiple vehicles. No derivative securities were reported in Table II, so this disclosure focuses completely on common equity exposure.

This kind of filing shows increased capital commitment from a board member and related investment vehicles over a narrow two-day window. The use of weighted average prices and trade ranges signals that these were executed as multiple market transactions rather than a single block. A practical item to watch is whether future Forms 4 continue to show net purchases or any subsequent sales by these same affiliated entities over the coming quarters.

Insider Trade Summary

Net Buyer: 822,613 shares ($3,600,784)

Net Buy 2 txns

Insider Satter Muneer A

Role Director

Bought 822,613 shs ($3.60M)

Type	Security	Shares	Price	Value
Purchase	Common Stock	422,613	$4.28	$1.81M
Purchase	Common Stock	400,000	$4.48	$1.79M

Holdings After Transaction: Common Stock — 9,728,637 shares (Indirect, See footnote)

Footnotes (1)

1. All shares were purchased by Alerce Medical Technology Partners, L.P. ("Alerce Medical"). The Reporting Person has sole voting and dispositive power over the shares held by Alerce Medical. The Reporting Person disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein. This transaction was executed in multiple trades in prices ranging from $4.25 to $5.065, inclusive. The price reported in Column 4 above reflects the weighted average purchase price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares purchased at each respective price within the range set forth in this footnote. As of November 21, 2025, includes (a) 240,000 shares that are held by the Muneer A. Satter Revocable Trust for which the Reporting Person serves as trustee and, in such capacity, has sole voting and dispositive power over all such shares, (b) 567,240 shares that are held by various other trusts and entities for which the Reporting Person serves as trustee, investment advisor or manager, as applicable, and, in each such capacity, has sole voting and dispositive power over all such shares, (c) 1,147,738 shares that are held by Satter Medical Technology Partners, L.P. for which the Reporting Person has sole voting and dispositive power over all such shares and (d) 7,773,659 shares that are held by Alerce Medical for which the Reporting Person has sole voting and dispositive power over all such shares. The Reporting Person disclaims beneficial ownership of all shares included under (b), (c) and (d) of this footnote, except to the extent of his pecuniary interest therein. This transaction was executed in multiple trades in prices ranging from $4.165 to $4.415, inclusive. The price reported in Column 4 above reflects the weighted average purchase price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares purchased at each respective price within the range set forth in this footnote.

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Satter Muneer A

(Last) (First) (Middle)

C/O ANNEXON, INC.

1400 SIERRA POINT PKWY, BLDG C, STE 200

(Street)

BRISBANE CA 94005

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Annexon, Inc. [ ANNX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
11/20/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/20/2025		P		400,000(1)	A	$4.48(2)	9,306,024	I	See footnote(3)
Common Stock	11/21/2025		P		422,613(1)	A	$4.28(4)	9,728,637	I	See footnote(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. All shares were purchased by Alerce Medical Technology Partners, L.P. ("Alerce Medical"). The Reporting Person has sole voting and dispositive power over the shares held by Alerce Medical. The Reporting Person disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.

2. This transaction was executed in multiple trades in prices ranging from $4.25 to $5.065, inclusive. The price reported in Column 4 above reflects the weighted average purchase price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares purchased at each respective price within the range set forth in this footnote.

3. As of November 21, 2025, includes (a) 240,000 shares that are held by the Muneer A. Satter Revocable Trust for which the Reporting Person serves as trustee and, in such capacity, has sole voting and dispositive power over all such shares, (b) 567,240 shares that are held by various other trusts and entities for which the Reporting Person serves as trustee, investment advisor or manager, as applicable, and, in each such capacity, has sole voting and dispositive power over all such shares, (c) 1,147,738 shares that are held by Satter Medical Technology Partners, L.P. for which the Reporting Person has sole voting and dispositive power over all such shares and (d) 7,773,659 shares that are held by Alerce Medical for which the Reporting Person has sole voting and dispositive power over all such shares. The Reporting Person disclaims beneficial ownership of all shares included under (b), (c) and (d) of this footnote, except to the extent of his pecuniary interest therein.

4. This transaction was executed in multiple trades in prices ranging from $4.165 to $4.415, inclusive. The price reported in Column 4 above reflects the weighted average purchase price. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares purchased at each respective price within the range set forth in this footnote.

	/s/ Muneer A. Satter	11/21/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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