[Form 4] Mineralys Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Mineralys Therapeutics, Inc. (MLYS) reported an insider transaction by a major shareholder group associated with Catalys Pacific. On 11/20/2025, an indirect holder reported the sale of 1,000,000 shares of Mineralys common stock at $43.35 per share, coded as an "S" transaction, which indicates a sale.

After this transaction, the reporting entities collectively reported 7,903,838 shares of Mineralys common stock beneficially owned on an indirect basis. The filing identifies the reporting persons as including a director and a 10% owner, with the shares held of record by Catalys Pacific Fund, LP and controlled through its general partner structure. The related entities and Brian Taylor Slingsby state that they may be deemed to have voting and investment power over these shares but disclaim beneficial ownership except to the extent of any pecuniary interest.

Insights

Equity ownership and insider-transactions analyst

Large insider sale by a 10% holder, but overall thesis impact is unclear.

The report shows an indirect holder associated with Catalys Pacific Fund, LP selling 1,000,000 shares of Mineralys Therapeutics (MLYS) common stock on 11/20/2025 at $43.35 per share. The transaction code "S" indicates this was an open-market or private sale of already-owned shares rather than an issuance by the company.

Following the sale, the filing lists 7,903,838 shares of Mineralys common stock as beneficially owned indirectly. The structure involves Catalys Pacific Fund, LP, its general partner Catalys Pacific Fund GP, LP, Catalys Pacific, LLC, and Brian Taylor Slingsby, who is also identified as a director and 10% owner. Each of these parties disclaims beneficial ownership beyond any pecuniary interest, which is common language for fund-related reporting.

The economic and governance impact depends on how this stake compares to Mineralys’s total shares outstanding and whether similar transactions recur. That context is not provided here, so this event is best interpreted as a significant liquidity move by an existing large holder rather than a clearly positive or negative signal for Mineralys’s core business.

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

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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^*

Slingsby Brian Taylor

(Last) (First) (Middle)

1700 WESTLAKE AVE. N, SUITE 200

THINKSPACE

(Street)

SEATTLE WA 98109

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Mineralys Therapeutics, Inc. [ MLYS ]

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

X	Director	X	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)

	Form filed by One Reporting Person
X	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		S		1,000,000	D	$43.35	7,903,838	I	See Footnote(1)

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

1. Name and Address of Reporting Person^*

Slingsby Brian Taylor

(Last) (First) (Middle)

1700 WESTLAKE AVE. N, SUITE 200

THINKSPACE

(Street)

SEATTLE WA 98109

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Catalys Pacific Fund, LP

(Last) (First) (Middle)

3RD FLOOR WHITEHALL HOUSE

238 NORTH CHURCH STREET

(Street)

GEORGE TOWN, GRAND CAYMAN E9 KY1-1107

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. Represents securities held directly by Catalys Pacific Fund, LP. The general partner of Catalys Pacific Fund, LP is Catalys Pacific Fund GP, LP. Brian Taylor Slingsby is the managing partner of Catalys Pacific, LLC, which is the general partner of Catalys Pacific Fund GP, LP. Catalys Pacific, LLC, Catalys Pacific Fund GP, LP and Brian Taylor Slingsby may be deemed to have voting and investment power over the shares held of record by Catalys Pacific Fund, LP. Each of Catalys Pacific, LLC, Catalys Pacific Fund GP, LP and Brian Taylor Slingsby disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.

Remarks:

	/s/ Brian Taylor Slingsby	11/21/2025
	Catalys Pacific Fund, LP, By: Catalys Pacific Fund GP, LP, its General Partner, By: Catalys Pacific, LLC, its General Partner, By: /s/ Brian Taylor Slingsby, its Managing Director	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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Mineralys Therapeutics (MLYS) report in this Form 4?

The filing reports that an indirect holder associated with Catalys Pacific Fund, LP sold 1,000,000 shares of Mineralys Therapeutics (MLYS) common stock on 11/20/2025. The sale was coded "S," indicating a sale of already-owned shares.

At what price were the Mineralys Therapeutics (MLYS) shares sold in the reported Form 4 transaction?

The 1,000,000 shares of Mineralys Therapeutics common stock were sold at a price of $43.35 per share, as disclosed in Table I of the Form 4.

How many Mineralys Therapeutics (MLYS) shares does the reporting group hold after the sale?

After the reported transaction, the Form 4 shows that the reporting group beneficially owns 7,903,838 shares of Mineralys Therapeutics common stock on an indirect basis.

Who is the reporting person in the Mineralys Therapeutics (MLYS) Form 4 and what is their relationship to the company?

The filing relates to holdings of Catalys Pacific Fund, LP and its affiliated entities, with Brian Taylor Slingsby signing as managing director of Catalys Pacific, LLC. The reporting person(s) are identified as a director and a 10% owner of Mineralys Therapeutics.

Do the reporting persons claim full beneficial ownership of the Mineralys Therapeutics (MLYS) shares?

No. The explanation states that Catalys Pacific, LLC, Catalys Pacific Fund GP, LP and Brian Taylor Slingsby may be deemed to have voting and investment power over the shares but disclaim beneficial ownership except to the extent of any pecuniary interest.

Does this Form 4 for Mineralys Therapeutics (MLYS) involve any derivative securities?

The Form 4 includes a section for derivative securities (Table II), but the provided excerpt does not list any specific derivative transactions; the detailed numbers shown relate to non-derivative common stock in Table I.