Caley Castelein - 28 Oct 2025 Form 4 Insider Report for Tourmaline Bio, Inc. (TRML)

Reporting relationship: Director
Issuer ticker: TRML
Reported as of: 28 Oct 2025
Net transaction value: $0
SEC form: 4
Accepted by SEC: 28 Oct 2025, 18:30:15 UTC
Prior SEC filing: 17 Oct 2025
Next SEC filing: 18 May 2026
Source filing: View source filing
Reporting owner signature: /s/ Brad Middlekauff, Attorney-in-Fact

Key filing fact

Caley Castelein filed Form 4 for Tourmaline Bio, Inc. (TRML) on 28 Oct 2025.

Key facts

This page summarizes Caley Castelein's Form 4 filing for Tourmaline Bio, Inc. (TRML).
5 reported transactions and 3 derivative rows are listed below.
Accepted by SEC: 28 Oct 2025, 18:30.

Change

Previous filing in this sequence was filed on 17 Oct 2025.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001355758 Primary reporting owner

Castelein Caley

Relationship: Director
Address: C/O TOURMALINE BIO, INC., 27 WEST 24TH STREET, SUITE 702, NEW YORK
Signature: /s/ Brad Middlekauff, Attorney-in-Fact
Signature date: 28 Oct 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

TRML transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -515,997
Change %: -100%
Price
Shares after: 0
Date: 28 Oct 2025
Ownership: Direct
Footnotes: F1, F2

TRML transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -431,939
Change %: -100%
Price
Shares after: 0
Date: 28 Oct 2025
Ownership: By KVP Capital, LP
Footnotes: F1, F2, F3

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

TRML transaction Derivative

Employee Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -10,000
Change %: -100%
Price
Shares after: 0
Date: 28 Oct 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 10,000
Exercise price: $9.46
Footnotes: F1, F4

TRML transaction Derivative

Employee Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -10,000
Change %: -100%
Price
Shares after: 0
Date: 28 Oct 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 10,000
Exercise price: $13.91
Footnotes: F1, F4

TRML transaction Derivative

Employee Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -16,800
Change %: -100%
Price
Shares after: 0
Date: 28 Oct 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 16,800
Exercise price: $18.73
Footnotes: F1, F4

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Caley Castelein is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 4 footnotes

Footnote F1

This Form 4 reports securities disposed pursuant to that certain Agreement and Plan of Merger (the "Merger Agreement"), dated as of September 8, 2025, by and among Issuer, Novartis AG, a company limited by shares (Aktiengesellschaft) incorporated under the laws of Switzerland ("Parent"), and Torino Merger Sub Inc., a Delaware corporation and indirect wholly owned subsidiary of Parent ("Merger Sub"). Pursuant to the Merger Agreement, on October 28, 2025, Merger Sub completed a cash tender offer to acquire all of the shares of common stock of the Issuer, par value $0.0001 (the "Shares"), issued and outstanding immediately prior to the effective time of the merger (the "Effective Time"), in exchange for $48.00 in cash per Share, subject to any applicable withholding of taxes (the "Merger Consideration").

Footnote F2

Pursuant to the terms of the Merger Agreement, each Share was tendered in exchange for $48.00 in cash per Share.

Footnote F3

These shares are held by KVP. The Reporting Person is the Managing Member of KVP Capital GP, LLC, the General Partner of KVP and, as such, has sole voting and investment power with respect to the shares held by KVP. The Reporting Person disclaims beneficial ownership of the shares held by KVP except to the extent of his pecuniary interest therein and this report is not an admission that the Reporting Person is the beneficial owner of these securities for purposes of Section 16 or for any other purpose.

Footnote F4

Pursuant to the terms of the Merger Agreement, each stock option that was outstanding and unexercised immediately prior to the Effective Time was automatically canceled and terminated and converted into the right to receive an amount in cash, without interest, equal to the product of (i) the amount by which the Merger Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares issuable upon exercise of such option or portion thereof, subject to any applicable withholding of taxes.