[Form 4] Kronos Bio, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Form 4 filing overview: Director and 10% owner Norbert W. Bischofberger reported the disposal of all Kronos Bio (KRON) equity holdings on 20 June 2025. The transactions were executed in connection with the previously announced merger between Kronos Bio and Concentra Biosciences completed on 18 June 2025.

Key details

• Common shares disposed: 10,802,138 held directly plus an aggregate 1,055,000 shares held through five family trusts (each trust disposed 263,750 shares).
• Consideration per share: US $0.57 cash plus one non-transferable contingent value right (CVR) as defined in the merger agreement.
• Derivative positions: Four option grants (total = 1,967,854 options; strike prices US $1.08–30.78) became fully vested and were cancelled. Cash was paid only where the strike price was below US $0.57; underwater options were forfeited with no value.
• Resulting ownership: Following the transactions, Bischofberger reports zero common shares and zero outstanding options.

The filing confirms logistical completion of equity transfers required by the merger and removes the insider’s Section 16 reporting obligations once KRON ceases to trade publicly.

Positive

• Merger completion confirmed, eliminating closing risk for shareholders expecting $0.57 cash plus CVR.
• Full vesting and cash settlement of in-the-money options provides immediate liquidity to insider and, by extension, validates treatment for all option holders.

Negative

• Underwater options (strike ≥ $0.57) cancelled with no consideration, erasing potential value for those grants.
• Public shareholders lose exposure to Kronos Bio as an independent entity; future upside limited to non-transferable CVR milestones.

Insights

M&A Specialist

TL;DR Insider Form 4 confirms tender-offer close; all shares/options cashed out at $0.57 + CVR, signalling final merger settlement.

The disclosure shows Concentra Biosciences has consummated its acquisition of Kronos Bio. Payment terms match the merger agreement, eliminating execution risk. Large insider ownership—over 10.8 million shares—has been surrendered, indicating full control transfer to the acquirer. The presence of CVRs preserves upside for legacy holders tied to future milestones, a typical mechanism in biotech takeouts. From a deal-process perspective, the filing removes a potential closing condition and supports remaining payouts to minority holders. Impact: positive for those tracking deal certainty; immaterial to future KRON trading since the stock will be delisted.

Portfolio Manager

TL;DR Insider exits at $0.57 cash; underwater options wiped—limited residual value for public investors beyond speculative CVR.

While the merger closes, the low cash price versus historical trading highs crystallises losses for long-term shareholders. Options with strikes above $0.57, including grants at $7.30 and $30.78, expired worthless, illustrating limited realised value. Investors now rely solely on CVR payments, which are contingent and illiquid. For portfolio managers, the event frees capital but offers no upside unless CVR milestones hit. Overall impact on returns is neutral to mildly negative depending on entry price.

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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X

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^*

BISCHOFBERGER NORBERT W

(Last) (First) (Middle)

C/O KRONOS BIO, INC.

301 BINNEY STREET, 2ND FLOOR EAST

(Street)

CAMBRIDGE MA 02142

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Kronos Bio, Inc. [ KRON ]

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)
06/20/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	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	06/20/2025		U		10,802,138(1)(2)	D	$0.57	0	I	See Footnote(3)
Common Stock	06/20/2025		U		263,750(1)(2)	D	$0.57	0	I	See Footnote(4)
Common Stock	06/20/2025		U		263,750(1)(2)	D	$0.57	0	I	See Footnote(5)
Common Stock	06/20/2025		U		263,750(1)(2)	D	$0.57	0	I	See Footnote(6)
Common Stock	06/20/2025		U		263,750(1)(2)	D	$0.57	0	I	See Footnote(7)

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
Employee Stock Option (Right to Buy)	$30.78	06/20/2025		D			297,186	(8)	12/09/2030	Common Stock	297,186	$0	0	D
Employee Stock Option (Right to Buy)	$7.3	06/20/2025		D			400,000	(8)	02/15/2032	Common Stock	400,000	$0	0	D
Employee Stock Option (Right to Buy)	$2.09	06/20/2025		D			570,868	(8)	02/14/2033	Common Stock	570,868	$0	0	D
Employee Stock Option (Right to Buy)	$1.08	06/20/2025		D			699,800	(8)	02/14/2034	Common Stock	699,800	$0	0	D

Explanation of Responses:

1. Disposed of pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated as of May 1, 2025, by and among Kronos Bio, Inc. (the "Issuer"), Concentra Biosciences, LLC ("Parent") and Concentra Merger Sub IV, Inc., a wholly owned subsidiary of Parent ("Merger Sub"). On June 18, 2025, Parent and Merger Sub completed a tender offer pursuant to the terms of the Merger Agreement for all outstanding shares of common stock of the Issuer (each, a "Share") for an offer price of (i) $0.57 per Share in cash (the "Cash Amount"), and (ii) one non-transferable contractual contingent value right (each, a "CVR"), subject to and in accordance with the terms of the Contingent Value Rights Agreement (the "CVR Agreement"), in each case, without interest, and subject to any applicable withholding taxes (the Cash Amount plus one CVR, collectively, the "Offer Price").[continues to Footnote 2]

2. [continues from Footnote 1] Merger Sub thereafter merged with and into the Issuer, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). At the effective time of the Merger, each issued and outstanding Share (other than any Excluded Shares (as such term is defined in the Merger Agreement)) was cancelled in exchange for the right to receive the Offer Price.

3. By the Norbert W. & Inger A. Bischofberger Revocable Inter Vivos Trust, dtd August 29, 1994,

4. By the Norbert W. Bischofberger and Inger A. Bischofberger, Trustees of The David Michael Anthony Dynasty GST Exempt Trust dated April 29, 2020.

5. By Norbert W. Bischofberger and Inger A. Bischofberger, Trustees of The David Michael Anthony Dynasty GST Non-Exempt Trust dated April 29, 2020.

6. By Norbert W. Bischofberger and Inger A. Bischofberger, Trustees of The Irene Alisha Bischofberger Dynasty GST Exempt Trust dated April 29, 2020.

7. By Norbert W. Bischofberger and Inger A. Bischofberger, Trustees of The Irene Alisha Bischofberger Dynasty GST Non-Exempt Trust dated April 29, 2020.

8. As of immediately prior to and conditioned upon the effective time of the effective time of the Merger, pursuant to the Merger Agreement, each outstanding option to purchase Shares (each, an "Option") became fully vested and exercisable, and to the extent not exercised prior to the effective time of the Merger, was cancelled and converted into the right to receive (a) an amount in cash (without interest and subject to deduction for any required withholding tax) equal to the product of (1) the excess, if any, of the Cash Amount over the exercise price per share of each such Option and (2) the number of Shares underlying such Option immediately prior to the effective time of the Merger and (b) one CVR in respect of each Share underlying such Option; provided, however, that if the exercise price per Share of any Option was equal to or greater than the Cash Amount that was then outstanding it was cancelled for no consideration.

	/s/ Norbert Bischofberger	06/20/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

Why did Norbert Bischofberger dispose of all KRON shares on 20 June 2025?

The shares were automatically exchanged for US $0.57 cash plus one CVR per share in connection with Kronos Bio’s merger with Concentra Biosciences.

How many Kronos Bio shares were reported as disposed in this Form 4?

10,802,138 shares held directly and 1,055,000 shares across five family trusts, totalling 11,857,138 shares.

What happened to the outstanding Kronos Bio stock options?

All 1,967,854 options vested; options with exercise prices below $0.57 were cashed out, while those at or above $0.57 were cancelled with no payout.

What consideration did shareholders receive in the Kronos Bio merger?

Each share received $0.57 in cash plus one non-transferable contingent value right (CVR) as outlined in the merger agreement.

Does this Form 4 affect Kronos Bio’s future SEC reporting status?

Yes. After the merger closes and shares are cancelled, the company will cease to be publicly traded, ending Section 16 filing obligations.