Kronos Bio Ends Equity Plans Following Concentra Biosciences Merger

Rhea-AI Filing Summary

Kronos Bio, Inc. (NASDAQ: KRON) filed five Post-Effective Amendment No. 1 filings to previously effective Form S-8 registration statements on 20 June 2025. The purpose is to deregister all unsold shares that had been reserved for issuance under the 2017 Equity Incentive Plan, the 2020 Equity Incentive Plan and the 2020 Employee Stock Purchase Plan.

The amendments follow the closing of the cash acquisition by Concentra Biosciences, LLC. Under the 1 May 2025 Agreement and Plan of Merger, completed on 20 June 2025, each outstanding Kronos share was converted into the right to receive $0.57 in cash plus one non-transferable contingent value right (CVR). With the merger consummated, Kronos has terminated all public offerings of its securities and is removing from registration every share that remains unissued under the five S-8 statements (originally covering millions of shares across the three plans).

As required by Rule 478 and the undertakings in each S-8, the filing formally ends the effectiveness of the registration statements, eliminating ongoing Exchange Act compliance obligations tied to those employee equity programs. The document is signed solely by Chief Financial Officer Michael Hearne pursuant to Securities Act Rule 478, reflecting Kronos’ new status as a wholly owned subsidiary and its exit from the public markets.

Positive

• Eliminates ongoing SEC compliance costs associated with maintaining five S-8 registration statements, potentially preserving cash for the private entity.

Negative

• Public shareholders no longer hold tradable equity; all shares were converted to $0.57 cash and a non-transferable CVR, ending market liquidity.

Insights

Corporate Governance Expert

TL;DR: Administrative deregistration finalises KRON’s exit from public equity markets; no direct value change for former public shareholders.

This filing is a procedural step automatically triggered once a company ceases to have public shareholders. By withdrawing the unsold shares from its S-8s, Kronos eliminates the possibility of future equity issuance under incentive plans and removes unnecessary SEC compliance costs. From a governance standpoint, the move is standard: the merger closed, the equity plans are effectively terminated, and the company is now private. No additional cash consideration, CVR terms, or changes to merger economics are introduced. Therefore, impact on investors is neutral—the economic outcome ($0.57 + CVR) was locked in at closing.

Portfolio Manager

TL;DR: Filing is housekeeping; publicly traded KRON shares are gone, cash/CVR payout already set—no trading opportunity remains.

From a portfolio perspective, this amendment carries negligible incremental impact. Investors who held KRON stock should already have received—or soon will receive—the merger cash and contingent value right. The deregistration does not alter payout timing or amount. It simply confirms the S-8 shelves are closed, preventing dilution that would otherwise have occurred via option exercises. The only residual potential value driver is the CVR, which trades privately and is non-transferable, so portfolio managers cannot position around this filing.

As filed with the Securities and Exchange Commission on June 20, 2025

Registration No. 333-278125

Registration No. 333-270564

Registration No. 333-262993

Registration No. 333-254620

Registration No. 333-249424

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-278125

POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-270564

POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-262993

POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-254620

POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-8 REGISTRATION STATEMENT NO. 333-249424

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

KRONOS BIO, INC.

(Exact name of registrant as specified in its charter)

Delaware		82-1895605
(State or other jurisdiction of incorporation or organization)		(IRS employer identification number)

301 Binney Street, 2nd Floor East

Cambridge, MA 02142

(Address of Principal Executive Offices, including Zip Code)

2017 Equity Incentive Plan (Prior Plan)

2020 Equity Incentive Plan

2020 Employee Stock Purchase Plan

(Full title of the Plans)

Michael Hearne

Chief Financial Officer

Kronos Bio Inc.

4747 Executive Drive, Suite 210

San Diego, California 92121

(858) 281-5372

(Name, Address and Telephone Number, including Area Code, of Agent for Service)

Copies to:

Ryan A. Murr

Gibson, Dunn & Crutcher LLP

One Embarcadero Center Suite 2600

San Francisco, California 94111

(415) 393-8200

Michael R. Patrone, Esq.

Amanda J. Gill, Esq.

Goodwin Procter LLP

New York Times Bldg

620 8th Ave

New York, NY 10018

(212) 813-8800

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See definitions of “large accelerated filer, “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		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 accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

EXPLANATORY NOTE

DEREGISTRATION OF UNSOLD SECURITIES

These Post-Effective Amendments (the “Post-Effective Amendments”) filed by Kronos Bio, Inc., a Delaware corporation (the “Registrant”), to deregister all shares of the Registrant’s common stock, $0.001 par value per share (the “Shares”), remaining unissued under the following Registration Statements on Form S-8 (each, a “Registration Statement”, and collectively, the “Registration Statements”) filed by the Registrant with the U.S. Securities and Exchange Commission (the “Commission”).

• Registration Statement on Form S-8 (No. 333-249424) pertaining to the registration of (i) 3,433,122 Shares issuable under the 2017 Equity Incentive Plan (the “2017 Plan”), (ii) 12,075,323 Shares issuable under the 2020 Equity Incentive Plan (the “2020 Plan”) and (iii) 688,000 Shares issuable under the 2020 Employee Stock Purchase Plan (the “ESPP”).

• Registration Statement on Form S-8 (No. 333-254620) pertaining to the registration of (i) 2,801,675 Shares issuable under the 2020 Plan and (ii) 560,335 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. 333-262993) pertaining to the registration of (i) 2,828,994 Shares issuable under the 2020 Plan and (ii) 565,798 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. 333-270564) pertaining to the registration of (i) 2,848,371 Shares issuable under the 2020 Plan and (ii) 569,674 Shares issuable under the ESPP.

• Registration Statement on Form S-8 (No. 333-278125) pertaining to the registration of (i) 2,947,329 Shares issuable under the 2020 Plan and (ii) 589,465 Shares issuable under the ESPP.

The Registrant is filing these Post-Effective Amendments to withdraw and remove any unissued and unsold securities issuable by Registration pursuant to the above-referenced Registration Statements.

On May 1, 2025, the Registrant entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Concentra Biosciences, LLC, a Delaware limited liability company (“Parent”), and Concentra Merger Sub IV, Inc., a Delaware corporation and wholly owned subsidiary of Parent (“Merger Sub”). Pursuant to the Merger Agreement, on June 20, 2025, Merger Sub was merged with and into the Registrant with the Registrant surviving as a wholly owned subsidiary of Parent (the “Merger”). In the Merger, each share of Common Stock (the “Shares”) (other than (i) Shares owned or held in the Company’s treasury immediately prior to the Effective Time, (ii) Shares owned directly or indirectly by Parent or Merger Sub immediately prior to the Effective Time and (iii) Shares held by any stockholder of the Registrant who properly exercised appraisal rights under Delaware law) was converted into the right to receive $0.57 in cash per Share, plus one non-transferrable contractual contingent value right for each Share.

As a result of the Merger, the Registrant has terminated all offerings of its securities pursuant to the Registration Statements. In accordance with an undertaking made by the Registrant in each of the Registration Statements to remove from registration, by means of a post-effective amendment, any of the securities that had been registered for issuance that remain unsold at the termination of the offerings, the Registrant hereby removes from registration all such securities registered under the Registration Statements that remain unsold as of the date hereof and terminates the effectiveness of the Registration Statements.

SIGNATURE

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused these Post-Effective Amendments to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of San Diego, State of California, on June 20, 2025. No other person is required to sign these Post-Effective Amendment to the Registration Statements in reliance on Rule 478 of the Securities Act of 1933, as amended.

KRONOS BIO, INC.

/s/ Michael Hearne

Name: Michael Hearne

Title: Chief Financial Officer

FAQ

Why did Kronos Bio (KRON) file Post-Effective Amendments to its Form S-8 statements?

Because the company was acquired by Concentra Biosciences and no longer plans to issue shares, it is deregistering all unsold securities under its equity incentive and ESPP plans.

How much did shareholders receive in the Kronos Bio takeover?

Each share was converted into $0.57 in cash plus one non-transferable contingent value right upon the 20 June 2025 merger closing.

Does this filing affect the value of the contingent value right (CVR)?

No. The Post-Effective Amendments only remove unsold shares from registration; they do not modify the CVR terms or payout.

Will Kronos Bio shares continue to trade after this filing?

No. Kronos is now a wholly owned subsidiary of Concentra Biosciences; its common stock has ceased trading and is deregistered.

What happens to outstanding employee stock options under the 2020 Plan?

All options either vested for cash consideration under the merger or were cancelled; no further exercises are possible after deregistration.