UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October ~~September 8~~28, 2025

TOURMALINE BIO, INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware		001-40384		83-2377352
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(I.R.S. Employer Identification No.)

27 West 24th Street, Suite 702 New York, NY				10010
27 West 24th Street Suite 702, New York, NY				10010
(Address of Principal Executive Offices)				(Zip Code)

Registrant’s Telephone Number, Including Area Code: (646) 481-9832

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		~~TradingSymbol~~Trading Symbol(s)		Name of each exchange on which registered
Common stock, par value $0.0001 per share		TRML		The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒ x

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

~~Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.~~Introductory Note

AsThis Current ~~previously~~Report ~~disclosed,~~on inForm 8-K ~~October~~is ~~2023,~~being ~~Tourmaline~~filed ~~Bio,~~in ~~Inc.,~~connection awith ~~Delaware corporation (~~the ~~“Company”),~~completion ~~adopted~~of anthe ~~Executive~~previously ~~Severance~~announced ~~and~~Merger ~~Change in Control Plan~~ (~~the~~as ~~“Severance~~defined ~~Plan”~~below). pursuant ~~Pursuant~~ to the ~~Severance~~Agreement ~~Plan~~ and ~~the participation agreements~~Plan ~~thereunder,~~of ifMerger, ~~within~~dated ~~the~~as 3of ~~month~~September 8, ~~period~~2025 ~~prior to or~~ (the ~~12 month period following a~~ “~~change~~Merger ~~in control~~Agreement”), by ~~(as~~and ~~defined~~among inTourmaline ~~the Severance Plan)~~Bio, Inc., wea ~~terminate~~Delaware ~~the~~corporation ~~employment of~~ (the ~~applicable executive without~~ “~~cause~~Company” ~~(excluding death or disability~~), orNovartis ~~such~~AG, ~~executive~~a ~~resigns~~company ~~for~~limited by ~~“good~~shares ~~reason”~~ (~~each,~~Aktiengesellschaft) asincorporated ~~defined~~under in the ~~Severance~~laws ~~Plan) and within no more than 60 days~~ of ~~such~~Switzerland ~~termination~~(“Parent”), ~~the executive executes~~ and ~~does~~Torino ~~not~~Merger Sub ~~revoke~~Inc., a ~~separation~~Delaware ~~agreement~~corporation and ~~release~~an ofindirect ~~claims,~~wholly ~~such~~owned ~~executive~~subsidiary ~~officer~~of ~~will~~Parent ~~be entitled to receive certain severance benefits~~(“Purchaser”).

OnPursuant ~~September 8,~~to ~~2025,~~ the ~~board~~Merger ofAgreement, upon ~~directors~~the ~~approved~~terms ~~certain~~and ~~amendments~~subject to the ~~benefits~~conditions ~~provided~~thereof, ~~under~~on ~~the~~September 29, ~~Severance~~2025, ~~Plan~~Purchaser incommenced ~~the event of~~ a ~~Covered~~cash ~~Termination~~tender ~~that~~offer ~~occurs during the Change in Control Period~~ (~~each, as defined in~~ the ~~Severance Plan~~“Offer”). to Asacquire aall ~~result~~ of the ~~amendment,~~outstanding inshares ~~the event~~ of acommon ~~Covered~~stock ~~Termination~~of ~~that occurs during~~ the ~~Change in Control Period~~Company, ~~Ryan~~par ~~Robinson,~~value ~~our~~$0.0001 ~~Chief~~per ~~Financial~~share ~~Officer and principal financial and accounting officer, and Brad Middlekauff, our Chief Business Officer and General Counsel, will each be entitled to receive~~ (~~i) a lump sum payment equal to~~ the ~~sum of (a~~“Shares”) ~~15 months of their respective then current annual base salary~~, at ~~and~~a ~~(b)~~price ~~125%~~ of ~~their~~$48.00 ~~respective~~per ~~annual~~Share ~~target~~in ~~bonus~~cash, ~~(ii) payment~~without orinterest ~~reimbursement of premiums to maintain group health insurance continuation benefits pursuant to COBRA for such executive~~ and ~~such~~subject ~~executive’s respective eligible dependents for up~~ to 15any ~~months,~~applicable ~~and~~withholding ~~(iii) vesting acceleration as to 100%~~ of taxes (the ~~then-unvested~~“Offer ~~shares~~Price”) and subject to ~~each of such named executive officer’s then-outstanding time-based equity awards (and in~~ the ~~case~~satisfaction ofor ~~awards~~waiver, ~~subject~~ to ~~performance-based vesting conditions, such performance-based awards shall vest as specified in~~ the ~~applicable~~extent ~~award~~permitted ~~agreement~~under ~~governing such award). The severance payments and benefits~~ applicable tolegal ~~Sandeep Kulkarni~~requirements, ~~M.D.,~~of ~~our~~certain ~~Chief~~conditions ~~Executive~~set ~~Officer and principal executive officer, were not changed~~ forth in ~~connection with~~ the ~~amendment.~~Merger ~~Except as described above, the other terms and conditions of the Severance Plan remain unchanged~~Agreement.

The ~~foregoing~~Offer ~~description~~expired ofat ~~the~~one minute ~~Severance~~following ~~Plan~~11:59 ~~does~~p.m., ~~not~~Eastern ~~purport~~Time, toon beOctober 27, ~~complete~~2025 (such date and istime, ~~qualified~~the “Expiration Time”) and was not extended. Computershare Trust Company, N.A., in its ~~entirety~~capacity byas ~~reference~~depositary tofor the ~~full~~Offer, ~~text~~advised Purchaser that, as of the Expiration ~~Severance~~Time, ~~Plan~~24,030,382 Shares had been validly tendered and ~~related~~not ~~participation~~validly ~~agreement~~withdrawn pursuant to the Offer, arepresenting ~~copy~~approximately 92.94% of ~~which~~the isthen ~~filed~~outstanding Shares. Accordingly, the Minimum Condition (as ~~Exhibit~~defined 10in the Merger Agreement) has been satisfied.1 toPurchaser has ~~the~~accepted ~~Company’s~~for ~~Current~~payment ~~Report~~all onShares ~~Form 8-K~~that ~~filed~~were ~~with~~validly tendered and not validly withdrawn pursuant to the ~~SEC~~Offer onprior ~~October 27,~~to ~~2023~~ the Expiration Time and ispayment ~~incorporated~~for bysuch ~~reference~~Shares ~~herein.~~has been or will be made promptly in accordance with the terms of the Offer.

1Following the completion of the Offer and the satisfaction or waiver of certain conditions set forth in the Merger Agreement, on October 28, 2025, Parent, Purchaser and the Company, pursuant to Section 251(h) of the General Corporation Law of the State of Delaware and without a vote of the Company’s stockholders, effected the merger of Purchaser with and into the Company pursuant to the Merger Agreement (the “Merger”), with the separate corporate existence of Purchaser ceasing and the Company surviving the Merger under the name “Tourmaline Bio, Inc.” as an indirect wholly owned subsidiary of Parent (the “Surviving Corporation”).

~~SIGNATURES~~The foregoing description of the Merger Agreement, the Merger and the transactions contemplated thereby contained in this Introductory Note, including the Merger, does not purport to be complete and is subject to and qualified in its entirety by reference to the Merger Agreement, which was filed as Exhibit 2.1 of the Current Report on Form 8-K filed by the Company with the SEC on September 9, 2025, and is incorporated by reference herein.

~~Pursuant~~Item to1.02 ~~the~~Termination ~~requirements~~ of ~~the~~a ~~Securities~~Material ~~Exchange~~Definitive ~~Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized~~Agreement.

The information set forth in the Introductory Note of this Current Report on Form 8-K is incorporated by reference into this Item 1.02.

2In connection with the closing of the transactions contemplated by the Merger Agreement (the “Closing”), on October 15, 2025, the Company provided written notice to Leerink Partners LLC (“Leerink”), as sales agent, of its election to terminate the Sales Agreement, dated November 7, 2024, by and between the Company and Leerink (the “ATM Sales Agreement”), with such termination contingent upon the Closing. As previously reported, pursuant to the terms of the ATM Sales Agreement, the Company could offer and sell up to $100.0 million of shares of its common stock, par value $0.0001 per share, from time to time through an “at the market” equity offering program under which Leerink would act as agent and/or principal.

Item 2.01 Completion of Acquisition or Disposition of Assets.

The information set forth in the Introductory Note, Item 3.01, Item 5.01 and Item 5.03 of this Current Report on Form 8-K is incorporated by reference into this Item 2.01.

At the effective time of the Merger (the “Effective Time”), each Share then outstanding (other than Shares (a) held by the Company or in the Company’s treasury (other than, in each case, Shares held in a fiduciary or agency capacity and beneficially owned by third parties), Parent, Purchaser, any other direct or indirect wholly owned subsidiary of Parent, or by stockholders of the Company who have properly exercised and perfected their statutory rights of appraisal under Delaware law, or (b) irrevocably accepted for purchase in the Offer (such Shares described in clause (a) and clause (b) of this paragraph, the “Excluded Shares”)) was cancelled and converted into the right to receive the Offer Price (the “Merger Consideration”).

Each (a) Company stock option (collectively, the “Options”) outstanding as of immediately prior to the Effective Time was automatically accelerated and became fully vested and exercisable immediately prior to, and contingent upon, the Effective Time and as of the Effective Time, each vested Option (after giving effect to such acceleration) that was outstanding and unexercised as of immediately before the Effective Time was automatically canceled and converted into the right to receive an amount in cash, without interest, equal to the product of (i) the total number of Shares subject to such Option immediately prior to the Effective Time, multiplied by (ii) the excess of the Merger Consideration over the exercise price payable per Share under such Option; (b) share of Company restricted stock outstanding as of immediately prior to the Effective time was automatically accelerated and became fully vested as of immediately prior to, and contingent upon, the Effective Time and was treated as a Share pursuant to the terms of the Merger Agreement; and (c) Company restricted stock unit award (collectively, the “RSU Awards”) outstanding as of immediately prior to the Effective Time, whether vested or unvested, was automatically cancelled and converted into the right to receive an amount in cash, without interest, equal to the product of (i) the total number of Shares issuable in settlement of such RSU Award immediately prior to the Effective Time, multiplied by (ii) the Merger Consideration. Each Option with an exercise price equal to or in excess of the Merger Consideration was automatically cancelled for no consideration.

Item 3.01 Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing.

The information set forth in the Introductory Note and Item 2.01 of this Current Report on Form 8-K is incorporated by reference into this Item 3.01.

In connection with the consummation of the Offer and the Merger, on October 28, 2025, the Company requested that the Nasdaq Global Select Market (“Nasdaq”) suspend the Shares from trading effective as of the open of trading on October 28, 2025, remove the Shares from listing on Nasdaq, and file with the SEC an application on Form 25 to report the delisting of the Shares from Nasdaq (the “Form 25”). After effectiveness of the Form 25, the Company intends to file with the SEC a Form 15 with respect to the Shares, requesting the deregistration of the Shares under Section 12(g) of the Exchange Act and the suspension of the Company’s reporting obligations under Sections 13 and 15(d) of the Exchange Act.

Item 3.03 Material Modification to Rights of Security Holders.

The information contained in the Introductory Note, Item 2.01, Item 3.01, Item 5.01 and Item 5.03 of this Current Report on Form 8-K is incorporated herein by reference into this Item 3.03.

From and after the Effective Time, holders of Shares (other than Excluded Shares) immediately prior to such time ceased to have any rights as stockholders of the Company (other than their right to receive the Merger Consideration for each Share held, pursuant to the Merger Agreement).

Item 5.01 Changes in Control of Registrant.

The information contained in the Introductory Note, Item 2.01, Item 3.01, Item 3.03, Item 5.02 and Item 5.03 of this Current Report on Form 8-K is incorporated herein by reference into this Item 5.01.

At the Effective Time, the Company became an indirect wholly owned subsidiary of Parent. As a result of Purchaser’s acquisition of the Shares pursuant to the Offer and the consummation of the Merger, a change of control of the Company occurred. Purchaser obtained the funds necessary to fund the acquisition through a variety of sources, including cash on hand provided by Parent and its controlled affiliates.

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

The information contained in the Introductory Note and Item 2.01 of this Current Report on Form 8-K is incorporated herein by reference into this Item 5.02.

Effective immediately following and contingent upon the consummation of the Merger, Caley Castelein, M.D., Aaron Kantoff, Sandeep Kulkarni, M.D., Mark McDade, Clay Siegall, Ph.D., Sapna Srivastava, Ph.D., and Parvinder Thiara resigned from his or her position as a member of the Company’s board of directors (the “Board”) and all committees thereof. Such resignations from the Board were in connection with the transactions contemplated by the Merger Agreement and were not a result of a disagreement with the Company on any matter relating to the Company’s operations, policies or practices or any other matter.

In addition, effective immediately following and contingent upon the consummation of the Merger, Sandeep Kulkarni, M.D., resigned as the Company’s Chief Executive Officer, Ryan Robinson resigned as the Company’s Chief Financial Officer, Brad Middlekauff, J.D., resigned as the Company’s Chief Business Officer and General Counsel, Susan Dana Jones, Ph.D., resigned as the Company’s Chief Technology Officer, and Kevin Johnson, Ph.D., resigned as the Company’s Chief Regulatory Officer. Such resignations were in connection with the transactions contemplated by the Merger Agreement and were not a result of a disagreement with the Company on any matter relating to the Company’s operations, policies or practices or any other matter.

At the Effective Time, in connection with the Merger and in accordance with the terms of the Merger Agreement, the directors of Purchaser, John McKenna and Eduard Marti, became the directors of the Surviving Corporation. Also in connection with the Merger and in accordance with the terms of the Merger Agreement, the following individuals became the officers of the Surviving Corporation: (i) John McKenna was appointed to serve as the President of the Company and (ii) Eduard Marti was appointed to serve as Vice President and Treasurer of the Company. Biographical information regarding such individuals can be found in Schedule I of the Offer to Purchase, which was filed as Exhibit (a)(1)(i) to the Tender Offer Statement on Schedule TO filed by Parent and Purchaser with the SEC on September 29, 2025, as subsequently amended, which information is incorporated by reference into this Item 5.02.

Item 5.03 Amendments to Articles of Incorporations or Bylaws, Change in Fiscal Year.

The information contained in the Introductory Note and Item 2.01 of this Current Report on Form 8-K is incorporated herein by reference into this Item 5.03.

Pursuant to the Merger Agreement, at the Effective Time, the certificate of incorporation of the Company (the “Certificate of Incorporation”) was amended and restated in its entirety. The Certificate of Incorporation is filed as Exhibit 3.1 to this Current Report on Form 8-K and is incorporated herein by reference.

In addition, pursuant to the Merger Agreement, at the Effective Time, the Company’s bylaws (the “Bylaws”) were amended and restated in their entirety. The Bylaws are filed as Exhibit 3.2 to this Current Report on Form 8-K and are incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d)        Exhibits

Exhibit No.		Description
2.1*		Agreement and Plan of Merger, dated as of September 8, 2025, by and among the Company, Parent and Purchaser (incorporated by reference to Exhibit 2.1 of the Current Report of Form 8-K filed by the Company with the SEC on September 9, 2025)
3.1		Amended and Restated Certificate of Incorporation of Tourmaline Bio, Inc. (filed herewith).
3.2		Amended and Restated Bylaws of Tourmaline Bio, Inc. (filed herewith).
104		Cover Page Interactive Data File (embedded with the Inline XBRL document)

* Certain exhibits and schedules have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The Company hereby undertakes to provide copies of any of the omitted exhibits and schedules upon request by the SEC.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	Tourmaline Bio, Inc.

	By:	/s/ Jaime Huertas
		Name: Jaime Huertas
		Title: Secretary

Dated: October 28, 2025

Tourmaline Bio, Inc.

Date: September 12, 2025

/s/ Ryan Robinson

Ryan Robinson

Chief Financial Officer

Filing Compare · Tourmaline Bio, Inc.