UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 orOR 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): March 612, 2025

ACELYRIN, INC.

(Exact name of registrant as specified in its charter)

Delaware	001-41696	85-2406735
(State or other jurisdictionof incorporation)	(CommissionFile Number)	(IRS EmployerIdentification No.)
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)
4149 Agoura Hills, California		91301
(Address of principal executive offices)		(Zip Code)

4149 Agoura Hills, California		91301
(Address of Principal Executive Offices)		(Zip Code)

(805) 456-4393

Registrant’s telephone number, including area code~~: (805) 456-4393~~

N/A

(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))

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

Title of each class		TradingSymbol(s)		Name of each exchangeon which registered
Common Stock, par value $0.00001 per share		SLRN		Nasdaq Global Select Market


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Preferred Stock Purchase Rights	SLRN	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 ☒

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~~financing accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

~~Item~~ITEM 71.01. ~~Regulation~~ENTRY FDINTO ~~Disclosure~~A MATERIAL DEFINITIVE AGREEMENT.

AsThe ~~previously~~information ~~disclosed,~~set onforth ~~February 6,~~under ~~2025, ACELYRIN, INC., a Delaware corporation (the~~ “~~Company”),~~Item ~~Alumis Inc~~3.~~, a Delaware corporation (“Alumis”), and Arrow Merger Sub, Inc~~03., aMaterial ~~Delaware~~Modification ~~corporation~~to ~~and~~Rights ~~a wholly owned subsidiary~~ of ~~Alumis~~Security ~~(“Merger Sub~~Holders”), ~~entered into an Agreement and Plan~~ of ~~Merger~~this ~~(the~~Current ~~“Merger~~Report ~~Agreement”),~~on ~~pursuant~~Form to8-K ~~which,~~with ~~among~~respect ~~other matters, and subject~~ to the ~~satisfaction~~entry orinto ~~waiver~~a ofRights ~~the conditions set forth in the Merger~~ Agreement, ~~Merger~~(as ~~Sub~~defined ~~will~~below) ~~merge~~is ~~with~~incorporated ~~and~~ into ~~the~~this ~~Company,~~Item ~~with~~1.01 ~~the~~by ~~Company continuing as a wholly owned subsidiary of Alumis and the surviving corporation of the merger (the “Merger”)~~reference.

OnITEM ~~March 6, 2025, the Company released a presentation related to the proposed Merger, a copy of which is attached as Exhibit 99~~3.103. toMATERIAL ~~this~~MODIFICATION ~~Current~~TO ~~Report~~RIGHTS onOF ~~Form~~SECURITY ~~8-K and is incorporated herein by reference~~HOLDERS.

~~The~~On ~~information~~March ~~contained~~12, in2025, ~~this~~the ~~Item~~Board 7of Directors (the “Board”) of ACELYRIN, INC.01, ~~including~~a ~~Exhibit~~Delaware ~~99.1~~corporation (the “Company”), isdeclared ~~being~~a ~~furnished~~dividend toof one right (a “Right”) for each of the ~~Securities~~Company’s issued and ~~Exchange~~outstanding ~~Commission~~shares ~~(the~~of common stock, par value $0.00001 per share (“~~SEC~~Common Stock”) ~~and~~. ~~shall~~The ~~not~~dividend will be ~~deemed~~paid to the stockholders of record at the close of business on March 24, 2025 (the “~~filed~~Record Date”). ~~for~~Each ~~purposes~~Right entitles the holder, subject to the terms of ~~Section 18~~the Rights Agreement, to purchase from the Company one one-thousandth of a share of the ~~Securities~~Company’s ~~Exchange~~Series ~~Act~~A Junior Participating Preferred Stock (the “Preferred Stock”) at a price of ~~1934,~~$16 as(the ~~amended~~“Exercise Price”), orsubject ~~incorporated~~to bycertain ~~reference~~adjustments. inThe ~~any~~terms ~~filing~~of ~~under~~the Rights are set forth in the ~~Securities~~Rights ~~Act~~Agreement, dated as of ~~1933~~March 13, as2025 ~~amended~~(the “Rights Agreement”), ~~except~~between asthe ~~shall~~Company beand ~~expressly~~Computershare ~~set~~Trust ~~forth~~Company, byN.A., ~~specific~~as ~~reference~~Rights inAgent ~~such~~(the ~~filing~~“Rights Agent”).

~~Item~~The 9Rights will not be exercisable until the close of business on the earlier to occur of the date that is (i) the 10th day following a public announcement or disclosure and a good faith determination by the Board that a person or a group of affiliated or associated persons has become an “Acquiring Person,” which is defined as a person or group of affiliated or associated persons who, at any time after the date of the Rights Agreement, have acquired, or obtained the right to acquire, beneficial ownership of 10% (or 20% in the case of a person who has reported or is required to report their beneficial ownership of the Company’s securities on a Schedule 13G under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) or more of the Company’s outstanding shares of Common Stock, subject to certain exceptions, and (ii) the 10th business day (or a later date as may be determined by action of the Board before a person or group becomes an Acquiring Person) following the first public announcement of an intention to commence, or following the commencement of, a tender offer or exchange offer the consummation of which would result in a person or group becoming an Acquiring Person (the earlier of such dates being called the “Distribution Date”).01 ~~Financial~~Any ~~Statements~~existing stockholder or group that beneficially owns 10% or more of the Common Stock will be grandfathered at its current ownership level, but the Rights will become exercisable if at any time after the announcement of the Rights Agreement such stockholder or group increases its ownership of shares of Common Stock by an amount equal to or greater than the greater of (i) 10% (or, in the case of passive institutional investors, 20%) and ~~Exhibits~~(ii) the sum of the lowest beneficial ownership of such person since the first public announcement of adoption of the Rights Plan plus one share of Common Stock. Certain synthetic interests in securities created by derivative positions, whether or not such interests are considered to be ownership of the underlying Common Stock or are reportable for purposes of Regulation 13D of the Securities Exchange Act of 1934, as amended, are treated as beneficial ownership of the number of shares of Common Stock equivalent to the economic exposure created by the derivative position, to the extent actual shares of the Common Stock are directly or indirectly held by counterparties to the derivatives contracts.

With respect to certificates representing shares of Common Stock outstanding as of the Record Date, until the close of business on the earliest of the Distribution Date, the Redemption Date (das defined below) ~~Exhibits~~and the Final Expiration Date (as defined below), the Rights will be evidenced by such certificates for shares of Common Stock registered in the names of the holders thereof, and not by separate Rights Certificates, as described further below. With respect to book entry shares of Common Stock outstanding as of the Record Date, until the close of business on the earliest of the Distribution Date, the Redemption Date and the Final Expiration Date, the Rights will be evidenced by the balances indicated in the book entry account system of the transfer agent for the Common Stock. Until the earlier of the Distribution Date, the Redemption Date and the Final Expiration Date, the surrender for transfer of any shares of Common Stock outstanding on the Record Date will also constitute the surrender for transfer of the Rights associated with such shares of Common Stock, and Rights (and the right to receive certificates therefor) will be transferrable only in connection with the transfer of shares of Common Stock. After the Distribution Date, separate certificates representing the Rights or book entry statements will be mailed to record holders of Common Stock on the Distribution Date, and such separate certificates or book entry statements alone will evidence the Rights.

Exhibit No.		Description
99.1		Presentation, dated as of March 6, 2025.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

The Rights, which are not exercisable until the Distribution Date, will expire on the earliest to occur of (i) the close of business on March 12, 2026 (the “Final Expiration Date”); (ii) the time at which the Rights are redeemed as provided in the Rights Agreement (the “Redemption Date”); (iii) the time at which the Rights are exchanged pursuant to the Rights Agreement; and (iv) the time at which the Rights are terminated upon the closing of any merger or other acquisition transaction involving the Company pursuant to a merger or other acquisition agreement that has been approved by the Board prior to any person becoming an Acquiring Person (the earliest of (i), (ii), (iii) and (iv) is referred to as the “Expiration Date”).

~~Forward~~Each share of Preferred Stock will be entitled to receive, when, as and if declared by the Board, a preferential per share quarterly dividend payment equal to the aggregate per share amount of all cash dividends, plus the aggregate per share amount (payable in kind) of all non-~~Looking~~cash ~~Statements~~dividends and other distributions (other than in shares of Common Stock), declared on the Common Stock during such quarter, adjusted to give effect to any dividend on any class of Company common stock payable in shares of such class of Company

~~This~~ common ~~communication~~stock ~~contains~~or ~~forward-looking~~any ~~statements~~subdivision, ~~within~~combination ~~the~~or ~~meaning~~reclassification of ~~federal~~such ~~securities~~class ~~laws,~~of ~~including~~Company ~~the~~common ~~“safe~~stock. ~~harbor”~~Each ~~provisions~~share of ~~the~~Preferred ~~Private~~Stock ~~Securities~~will ~~Litigation~~entitle ~~Reform~~the ~~Act~~holder ofthereof ~~1995.~~to ~~Such~~1,000 ~~statements~~votes ~~are~~on ~~based~~all ~~upon~~matters ~~current~~submitted ~~plans,~~to ~~estimates~~a ~~and~~vote ~~expectations~~ of ~~management~~the stockholders of ~~Alumis and~~ the Company. inIn ~~light~~the event of ~~historical~~any ~~results and trends~~merger, ~~current~~consolidation ~~conditions~~or ~~and~~other ~~potential~~transaction ~~future~~in ~~developments,~~which ~~and~~shares ~~are~~of ~~subject~~Common toStock ~~various~~are ~~risks~~converted ~~and~~or ~~uncertainties~~exchanged, ~~that~~each ~~could~~share ~~cause actual results to differ materially from such statements. The inclusion~~ of ~~forward-looking~~Preferred ~~statements~~Stock ~~should~~will ~~not~~ be ~~regarded~~entitled asto receive a ~~representation~~preferential ~~that~~liquidation ~~such~~payment ~~plans,~~equal ~~estimates~~to ~~and expectations will be achieved. Words such as “anticipate~~1,”000 ~~“expect,”~~times ~~“project,”~~the ~~“intend,”~~aggregate ~~“believe,”~~amount ~~“may,”~~to ~~“will,”~~be ~~“should,”~~distributed ~~“plan,”~~per ~~“could,”~~share ~~“continue,”~~to ~~“target,”~~holders ~~“contemplate,”~~of ~~“estimate,”~~shares ~~“forecast,”~~of ~~“guidance,”~~Common ~~“predict,”~~Stock ~~“possible,”~~plus ~~“potential,”~~an ~~“pursue,”~~amount ~~“likely,”~~equal ~~and~~to ~~words~~accrued and ~~terms~~unpaid ofdividends ~~similar~~and ~~substance~~distributions ~~used~~on insuch ~~connection~~share ~~with any discussion~~ of ~~future~~Preferred ~~plans~~Stock, ~~actions~~whether or ~~events~~not ~~identify forward-looking statements. All statements~~declared, ~~other~~to ~~than statements of historical facts, including express or implied statements regarding~~ the ~~proposed~~date ~~Merger; the conversion~~ of ~~equity~~such ~~interests~~payment ~~contemplated~~(adjusted byto ~~the~~give ~~Merger~~effect ~~Agreement;~~to ~~the~~any ~~issuance~~dilution ofevent). ~~common~~The ~~stock~~Preferred ofStock ~~Alumis~~has ~~contemplated~~been bystructured ~~the~~so ~~Merger~~that ~~Agreement;~~each ~~the~~share ~~expected filing by Alumis with the SEC~~ of aPreferred ~~registration~~Stock ~~statement~~has ondividend, ~~Form~~liquidation ~~S-4 (the “Registration Statement”)~~ and avoting ~~joint~~rights ~~proxy~~equal ~~statement/prospectus of Alumis and ACELYRIN~~ to bethose ~~included therein (the “Joint Proxy Statement/Prospectus”); the expected timing~~ of ~~the~~1,000 ~~closing~~shares of ~~the~~Common ~~proposed~~Stock. ~~Merger;~~Accordingly, the ~~ability~~value of ~~the~~one-one ~~parties~~thousandth tointerest ~~complete~~in ~~the~~a ~~proposed~~share ~~Merger considering the various closing conditions; the expected benefits~~ of ~~the~~Preferred ~~proposed~~Stock ~~Merger;~~purchasable ~~the~~upon ~~sufficiency~~exercise of ~~the~~each ~~combined~~Right ~~company’s~~approximates ~~capital resources;~~ the ~~competitive~~value ~~ability and position~~ of ~~the~~one ~~combined~~share ~~company; and any assumptions underlying any~~ of ~~the~~Common ~~foregoing, are forward-looking statements~~Stock.

~~Risks~~The ~~and~~Exercise ~~uncertainties~~Price ~~include~~payable, ~~among~~and ~~other things, (i)~~ the ~~risk~~number ~~that~~of ~~the~~shares ~~proposed~~of ~~Merger~~Preferred ~~may~~Stock ~~not~~or beother ~~completed~~securities ~~in a timely basis~~ or atproperty ~~all~~issuable, ~~which~~upon ~~may~~exercise ~~adversely~~of ~~affect Alumis’ and~~ the ~~Company’s~~Rights ~~businesses~~are ~~and~~subject ~~the~~to ~~price~~adjustment offrom ~~their~~time ~~respective~~to ~~securities;~~time ~~(ii) the potential failure~~ to ~~receive,~~prevent ondilution. aThe ~~timely~~number ~~basis~~of orRights ~~otherwise,~~and the ~~required~~number ~~approvals~~ of ~~the~~one ~~proposed~~one-thousandths ~~Merger,~~of ~~including~~a ~~stockholder~~share ~~approvals~~of byPreferred ~~both~~Stock ~~Alumis’~~issuable ~~stockholders~~upon ~~and~~exercise ~~the~~of ~~Company’s~~each ~~stockholders,~~Right ~~and~~are ~~the~~also ~~potential~~subject ~~failure~~ to ~~satisfy~~adjustment ~~the~~upon ~~other~~certain ~~conditions~~events tooccurring ~~the~~before ~~consummation of~~ the ~~transaction;~~Distribution ~~(iii) the~~Date.

~~effect~~In of the ~~announcement,~~event pendency or completion of the proposed Merger on each of Alumis’ or the Company’s ability to attract, motivate, retain and hire key personnel and maintain relationships with partners, suppliers and others with whom Alumis or the Company does business, or on Alumis’ or the Company’s operating results and business generally; (iv) that ~~the proposed Merger may divert management’s attention from each of Alumis’ and the Company’s ongoing business operations; (v) the risk of~~ any ~~legal~~person ~~proceedings related to the proposed Merger~~ or ~~otherwise,~~a orgroup ~~the impact~~ of ~~the~~affiliated ~~proposed Merger thereupon, including resulting expense~~ or ~~delay;~~associated ~~(vi) that~~persons ~~Alumis~~becomes oran ~~the~~Acquiring ~~Company~~Person ~~may~~after ~~be adversely affected by other economic, business and/or competitive factors; (vii)~~ the ~~occurrence~~date of ~~any event, change or other circumstance that could give rise to~~ the ~~termination~~Rights ~~of the Merger~~ Agreement, ~~including~~each inholder ~~circumstances~~of ~~which would require Alumis or the Company to pay~~ a ~~termination~~Right, ~~fee;~~other ~~(viii) the~~than ~~risk~~Rights ~~that~~beneficially ~~restrictions~~owned ~~during~~by ~~the~~an ~~pendency~~Acquiring ofPerson ~~the proposed Merger may impact Alumis’ or the Company’s ability to pursue certain business opportunities or strategic transactions;~~ (~~ix) the risk that the anticipated benefits~~ and ~~synergies of~~ the ~~proposed Merger may not be fully realized or may take longer to realize than expected; (x) the impact of legislative~~affiliates, ~~regulatory,~~associates ~~economic, competitive~~ and ~~technological~~certain ~~changes;~~transferees ~~(xi) risks relating to the value~~ of ~~Alumis~~such ~~securities~~Acquiring toPerson) ~~be issued in the proposed Merger;~~ (~~xii) the~~which ~~risk~~rights ~~that~~will ~~integration~~thereafter ~~of the proposed Merger post-closing may not occur as anticipated or the combined company may not~~ be ~~able~~null to achieve the growth prospects expected from the transaction; (xiii) the effect of the announcement, pendency or completion of the proposed Merger on the market price of the common stock of each of Alumis and ~~the Company; (xiv~~void) ~~the implementation of each of Alumis’ and the Company’s business model and strategic plans for product candidates and pipeline~~, ~~and~~will ~~challenges~~thereafter ~~inherent~~have ~~in developing, commercializing, manufacturing, launching, marketing and selling potential existing and new products and product candidates; (xv)~~ the ~~scope,~~right progress, results and costs of developing Alumis’ and the Company’s product candidates and any future product candidates, including conducting preclinical studies and clinical trials, and otherwise related to ~~the~~receive ~~research~~upon ~~and~~exercise ~~development of Alumis’~~ and ~~the~~payment Company’s pipeline; (xvi) the timing and costs involved in obtaining and maintaining regulatory approval for Alumis’ and the Company’s current or future product candidates, and any related restrictions, limitations and/or warnings in the label of ~~any approved product; (xvii)~~ the ~~market~~Exercise ~~for,~~Price ~~adoption~~that ~~(including~~number ~~rate and degree~~ of ~~market~~shares ~~acceptance) and pricing and reimbursement~~ of ~~Alumis’~~Common ~~and~~Stock ~~the Company’s product candidates, if approved, and their respective abilities to compete with therapies and procedures that are rapidly growing and evolving;~~ (~~xviii) uncertainties in contractual relationships, including collaborations, partnerships, licensing~~ or other ~~arrangements~~equivalent ~~and the performance of third-party suppliers and manufacturers; (xix~~securities) ~~the~~ ~~ability~~having ofa ~~each~~market ofvalue ~~Alumis~~equal ~~and the Company~~ to ~~establish~~two ~~and~~times ~~maintain intellectual property protection for products or avoid or defend claims of infringement; (xx) Alumis’ ability to successfully integrate~~ the ~~Company’s~~Exercise ~~operations and personnel; and (xxi) potential delays in initiating, enrolling or completing preclinical studies and clinical trials~~Price.

~~These~~In ~~risks, as well as other risks related to~~ the ~~proposed~~event ~~Merger,~~that ~~will~~any beperson ~~described~~or ina ~~the~~group ~~Registration~~of ~~Statement~~affiliated ~~and~~or ~~the~~associated ~~Joint~~persons ~~Proxy~~becomes ~~Statement/Prospectus.~~an ~~While~~Acquiring ~~the~~Person ~~list of factors presented here~~ and the ~~list~~Company ofmerges ~~factors~~into toor beengages ~~presented~~ in ~~the~~certain ~~Registration~~other ~~Statement~~business ~~are~~combinations ~~considered~~with ~~representative,~~any noperson ~~such~~or ~~list should be considered to be~~ a ~~complete~~group ~~statement~~ of ~~all~~affiliated ~~potential~~or ~~risks~~associated ~~and uncertainties. For additional information about other factors that could cause actual results to differ materially from those described in the forward-looking statements~~persons, ~~please~~or ~~refer~~50% toor ~~Alumis’~~more ~~and~~of the Company’s ~~respective~~consolidated ~~periodic~~assets ~~reports~~or ~~and~~earning ~~other~~power ~~filings~~are ~~with~~sold ~~the~~to ~~SEC,~~any ~~including~~person ~~the~~or ~~risk~~a ~~factors~~group ~~identified~~of inaffiliated ~~Alumis’ and the Company’s most recent Quarterly Reports on Form 10-Q and/~~or ~~Annual~~associated ~~Reports~~persons, oneach ~~Form 10-K.~~holder ~~The~~of ~~risks~~a ~~and~~Right, ~~uncertainties~~other ~~described~~than ~~above~~Rights ~~and~~owned inby ~~the~~an ~~SEC~~Acquiring ~~filings~~Person ~~cited above are not exclusive~~ (and ~~further information concerning Alumis and~~ the ~~Company and their respective businesses~~affiliates, ~~including~~associates ~~factors~~and ~~that~~certain ~~potentially~~transferees ~~could~~of ~~materially~~such ~~affect~~Acquiring ~~their respective businesses~~Person), ~~financial~~will ~~conditions~~thereafter orhave ~~operating~~the ~~results,~~right ~~may emerge from time~~ to ~~time.~~receive, ~~Readers~~upon ~~are~~exercise ~~urged to consider these factors carefully in evaluating these forward-looking statements,~~ and ~~not~~payment toof ~~place~~the ~~undue~~exercise ~~reliance on any forward-looking statements~~price, ~~which~~that ~~speak~~number ~~only~~of asshares of ~~the~~common ~~date~~stock ~~hereof.~~of ~~Readers should also carefully review~~ the ~~risk~~acquiring ~~factors~~company ~~described~~having ina ~~other~~market ~~documents~~value ~~Alumis~~at ~~and~~ the ~~Company~~time ~~file~~of ~~from~~that ~~time~~transaction equal to ~~time~~two ~~with~~times the ~~SEC~~Exercise Price.

~~The~~At ~~forward-looking~~any ~~statements~~time ~~included~~after inany ~~this~~person ~~communication~~or ~~are~~group ~~made~~of ~~only~~affiliated asor associated persons becomes an Acquiring Person and prior to such person or group acquiring a majority of the ~~date~~outstanding ~~hereof.~~shares ~~The~~of ~~Company~~Common ~~assumes~~Stock, nothe ~~obligation~~Board, ~~and~~at ~~does~~its ~~not~~option, ~~intend~~may toexchange ~~update~~each ~~these~~Right ~~forward-looking~~(other ~~statements~~than Rights owned by the Acquiring Person) in whole or in part, ~~even~~at ifan ~~new~~exchange ~~information~~ratio ~~becomes~~of ~~available~~one share of Common Stock per outstanding Right (subject to adjustment). No fractional shares of Common Stock will be issued and, in ~~the~~lieu ~~future~~thereof, ~~except~~an asadjustment ~~required~~in bycash ~~law~~will be made based on the market price of the Common Stock on the last trading day prior to the date of exchange.

~~Additional~~At ~~Information~~any time before any person or group of affiliated or associated persons becomes an Acquiring Person, the Board may redeem the Rights in whole, but not in part, at a price of $0.00001 per Right (subject to certain adjustments, the “Redemption Price”) and ~~Where~~on such terms and conditions as the Board may establish. After the period for redemption of the Rights has expired, the Board may not amend the Rights Agreement to ~~Find~~extend Itthe period for redemption of the Rights.

InImmediately ~~connection~~upon ~~with~~ the ~~proposed~~action ~~Merger,~~of ~~Alumis~~the ~~intends~~Board electing to ~~file~~redeem ~~with~~or exchange the ~~SEC~~Rights, the ~~Registration~~right ~~Statement,~~to ~~which~~exercise the Rights will ~~include~~terminate and the ~~Joint~~only ~~Proxy~~right ~~Statement/Prospectus.~~of ~~After~~ the ~~Registration~~holders ~~Statement~~of ~~has~~Rights ~~been~~will ~~declared~~be ~~effective~~to byreceive the ~~SEC,~~Redemption ~~the~~Price. ~~Joint~~The ~~Proxy~~Company ~~Statement/Prospectus~~shall ~~will~~promptly begive ~~delivered~~public tonotice ~~stockholders~~ of ~~Alumis~~any ~~and~~such ~~the Company~~redemption.

~~BEFORE~~Until ~~MAKING~~a ~~ANY~~Right ~~VOTING~~is ORexercised ~~INVESTMENT~~or ~~DECISION~~exchanged, SECURITY HOLDERS OF ALUMIS AND THE COMPANY ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS (INCLUDING ALL AMENDMENTS AND SUPPLEMENTS THERETO) AND OTHER DOCUMENTS RELATING TO THE MERGER THAT WILL BE FILED WITH THE SEC WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED MERGER. Investors and security holders will be able to obtain copies of the ~~joint~~holder ~~proxy statement/prospectus (when available) and other documents filed by Alumis and the Company with the SEC~~thereof, ~~without~~as ~~charge~~such, ~~through the website maintained by the SEC at www.sec.gov. Copies of the documents filed with the SEC by Alumis~~ will behave ~~available~~no ~~free~~rights ofas ~~charge~~a ~~under~~stockholder ~~the SEC Filings heading~~ of the ~~Investor Relations section of Alumis’ website at investors.alumis.com. Copies of the documents filed with the SEC by the~~ Company, ~~will~~including, bewithout ~~available~~limitation, ~~free of charge under~~ the ~~Financials &~~right ~~Filings~~to ~~heading~~vote ofor ~~the~~to ~~Investor~~receive ~~Relations section of the Company’s website investors~~dividends.~~acelyrin.com.~~

~~Participants~~The Company may amend or supplement the Rights Agreement without the approval of any holders of Rights in order to cure any ambiguity, to correct or supplement inconsistent or defective provisions, or to make any changes to or delete any provision of the ~~Solicitation~~Rights Agreement (or adopt any other provisions with respect to the Rights) that the Company deems necessary or desirable. However, from and after such time as any person or group of affiliated or associated persons becomes an Acquiring Person, the Rights Agreement shall not be amended or supplemented in any manner that would adversely affect the interests of the holders of Rights (other than an Acquiring Person and its affiliates and associates and any transferee of the Acquiring Person or its affiliates and its associates). For the avoidance of doubt, the Company shall be entitled to adopt and implement such procedures and arrangements (including with third parties) as it may deem necessary or desirable to facilitate the exercise, exchange, trading, issuance or distribution of the Rights (and shares of Preferred Stock) as contemplated in the Rights Agreement and to ensure that an Acquiring Person does not obtain the benefits thereof, and amendments in respect of the foregoing shall not be deemed to adversely affect the interests of the holders of Rights.

~~Alumis~~The ~~and~~Rights ~~the~~Agreement ~~Company~~is ~~and~~attached ~~their~~hereto ~~respective~~as ~~directors~~Exhibit ~~and executive officers may be deemed to be participants in the solicitation of proxies in respect of the proposed Merger~~4.1 ~~Information about Alumis’ directors~~ and ~~executive officers~~ is ~~set~~incorporated ~~forth~~herein inby ~~Alumis’ registration statement on Form S-1/A (File No~~reference. ~~333-280068),~~ ~~which~~The ~~was~~description ~~filed~~of ~~with~~ the ~~SEC~~Rights onAgreement ~~June 24,~~herein ~~2024.~~does ~~Information~~not ~~about~~purport ~~the~~to ~~Company’s~~be ~~directors~~complete and ~~executive officers~~ is ~~set~~qualified ~~forth~~ in ~~the~~its ~~proxy~~entirety statement for the Company’s 2024 Annual Meeting of Stockholders, which was filed with the SEC on April 22, 2024, and the Company’s Current Reports on Form 8-K filed with the SEC on May 28, 2024, August 13, 2024 and December 10, 2024. Stockholders may obtain additional information regarding the interests of such participants by ~~reading~~reference ~~the Registration Statement and the Joint Proxy Statement/Prospectus and other relevant materials~~ to beExhibit ~~filed with the SEC regarding the proposed merger when they become available~~4. ~~Investors should read the joint proxy statement/prospectus carefully when it becomes available before making any voting or investment decisions~~1.

NoITEM ~~Offer~~5.03. orAMENDMENTS ~~Solicitation~~TO ARTICLES OF INCORPORATION OR BYLAWS; CHANGE IN FISCAL YEAR.

~~This~~In ~~communication~~connection ~~shall~~with ~~not~~the ~~constitute~~adoption anof ~~offer~~the toRights ~~sell~~Agreement, or the ~~solicitation~~Board approved a Certificate of anDesignations ~~offer~~of toSeries ~~buy~~A ~~any~~Junior ~~securities~~Participating orPreferred aStock ~~solicitation~~(the “Certificate of ~~any~~Designations”). ~~vote~~The orCertificate ~~approval,~~of ~~nor~~Designations ~~shall~~is ~~there~~filed bewith ~~any~~the ~~sale~~Secretary of ~~securities~~State inof ~~any~~the ~~jurisdiction~~State of Delaware. See the description in ~~which~~Item ~~such~~3.03 ~~offer,~~of ~~solicitation~~this orCurrent ~~sale~~Report ~~would~~on beForm ~~unlawful~~8-K ~~prior~~for toa ~~registration~~more orcomplete ~~qualification~~description ~~under~~of the ~~securities~~rights ~~laws~~and preferences of ~~any~~the ~~such~~Preferred ~~jurisdiction~~Stock. NoThe ~~offering~~Certificate of ~~securities~~Designations ~~shall~~is beattached ~~made~~hereto ~~except~~as byExhibit ~~means~~3.1 ofand ais ~~prospectus~~incorporated ~~meeting~~herein ~~the~~by ~~requirements~~reference. ofThe ~~Section 10~~description of the ~~Securities~~Certificate ~~Act~~ of ~~1933,~~Designations asherein ~~amended~~does not purport to be complete and is qualified in its entirety by Exhibit 3.1.

~~SIGNATURE~~ITEM 8.01. OTHER EVENTS.

On March 13, 2025, the Company issued a press release announcing the adoption of the Rights Agreement and the declaration of the dividend of the Rights. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

ITEM 9.01.

FINANCIAL STATEMENTS AND EXHIBITS.

(d) Exhibits.


3.1		Certificate of Designations of Series A Junior Participating Preferred Stock of ACELYRIN, INC.

4.1		Rights Agreement, dated as of March 13, 2025, between ACELYRIN, INC. and Computershare Trust Company, N.A. as Rights Agent

99.1		Press Release of ACELYRIN, INC., dated March 13, 2025

104		Cover Page Interactive Data File (embedded within the Inline XBRL document)

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 hereunto duly authorized.

Date: March 6, 2025

ACELYRIN, INC.

ACELYRIN, INC.

/s/ Amar Murugan

Date: March 13, 2025

/s/ Amar Murugan

Amar Murugan

Chief Legal Officer

Filing Compare · ACELYRIN, Inc.