[SCHEDULE 13G/A] MBX Biosciences, Inc. SEC Filing

Rhea-AI Filing Summary

Deep Track Capital, Deep Track Biotechnology Master Fund and David Kroin report shared beneficial ownership of 2,188,592 common shares of MBX Biosciences, representing 6.55% of the outstanding common stock. The filing shows the reporting persons hold shared voting and shared dispositive power over these shares, and the percent is calculated using 33,424,371 shares outstanding per the issuer's disclosure. The statement is a joint filing under Schedule 13G, identifying the reporting persons and their filing classifications (Deep Track Capital: IA, OO; Deep Track Biotechnology Master Fund: CO; David Kroin: HC, IN), and certifies the holdings were not acquired to change or influence control.

Insights

Financial Analyst

TL;DR: A disclosed 6.55% position through shared voting/dispositive power is material and must be monitored by investors.

The reporting persons collectively hold 2,188,592 MBX shares, equal to 6.55% of the outstanding common stock based on the issuer's disclosed share count. That percentage crosses the 5% reporting threshold and signals a significant minority stake with shared control rights rather than sole control. For investors, the immediate implication is increased ownership concentration and transparency about who can influence votes or dispositions of this block.

Corporate Governance Expert

TL;DR: Joint Schedule 13G filing shows coordinated disclosure and shared authority, relevant to governance and voting outcomes.

The filing is presented as a joint statement under Rule 13d-1(k), indicating the undersigned acknowledge the statement is filed on behalf of each reporting person. The record shows shared voting and dispositive power over the same 2,188,592 shares by the two entities and an individual. The classifications listed (IA, OO; CO; HC, IN) clarify the roles of the filers but do not themselves indicate changes to board composition or corporate control.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

MBX Biosciences, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

55287L101

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 55287L101

1

Names of Reporting Persons

Deep Track Capital, LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,188,592.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,188,592.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,188,592.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.55 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP No. 55287L101

1

Names of Reporting Persons

Deep Track Biotechnology Master Fund, Ltd.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,188,592.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,188,592.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,188,592.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.55 %

12

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13G

CUSIP No. 55287L101

1

Names of Reporting Persons

David Kroin

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,188,592.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,188,592.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,188,592.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.55 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MBX Biosciences, Inc.
(b)	Address of issuer's principal executive offices: 11711 N. Meridian Street, Suite 300, Carmel, Indiana 46032
Item 2.
(a)	Name of person filing: (i) Deep Track Capital, LP (ii) Deep Track Biotechnology Master Fund, Ltd. (iii) David Kroin
(b)	Address or principal business office or, if none, residence: (i) 200 Greenwich Ave, 3rd Floor, Greenwich, CT 06830 (ii) c/o Walkers Corporate Limited, 190 Elgin Ave, George Town, KY1-9001, Cayman Islands (iii) c/o Deep Track Capital, LP, 200 Greenwich Ave, 3rd Floor, Greenwich, CT 06830
(c)	Citizenship: (i) Delaware (ii) Cayman Islands (iii) United States
(d)	Title of class of securities: Common Stock, $0.0001 par value per share
(e)	CUSIP No.: 55287L101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2,188,592
(b)	Percent of class: 6.55%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 2,188,592
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 2,188,592
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. Deep Track Capital, LP is the relevant entity for which David Kroin may be considered a control person.
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Deep Track Capital, LP

Signature:	/s/ David Kroin
Name/Title:	David Kroin, Managing Member of the General Partner of the Investment Adviser
Date:	08/14/2025

Deep Track Biotechnology Master Fund, Ltd.

Signature:	/s/ David Kroin
Name/Title:	David Kroin, Director
Date:	08/14/2025

David Kroin

Signature:	/s/ David Kroin
Name/Title:	David Kroin
Date:	08/14/2025

Exhibit Information

Item 4: Information with respect to the Reporting Persons' ownership of the Ordinary Shares as of August 14, 2025, is incorporated by reference to items (5) - (9) and (11) of the cover page of the respective Reporting Person. The amount beneficially owned by each Reporting Person is determined based on 33,424,371 common stock outstanding as of May 8, 2025, according to the issuer's Form 10-Q filed with the SEC on May 12, 2025. JOINT FILING STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on SCHEDULE 13G, is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on SCHEDULE 13G, shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate. Dated: August 14, 2025 Deep Track Capital, LP By: /s/ David Kroin David Kroin, Managing Member of the General Partner of the Investment Adviser Deep Track Biotechnology Master Fund, Ltd. By: /s/ David Kroin David Kroin, Director David Kroin By: /s/ David Kroin David Kroin

FAQ

How many MBX shares do Deep Track entities and David Kroin report owning?

They report beneficial ownership of 2,188,592 common shares of MBX.

What percentage of MBX does the reported stake represent?

The reported stake represents 6.55% of the outstanding common stock.

On what share count is the 6.55% based?

The percentage is calculated using a total of 33,424,371 common shares outstanding per the issuer's disclosure.

Do the reporting persons have sole or shared voting power over the shares?

The filing states they have shared voting power and shared dispositive power over the reported shares, with no sole voting or dispositive power reported.

What types of reporting persons are named in the MBX Schedule 13G?

Classifications listed include IA, OO for Deep Track Capital, CO for Deep Track Biotechnology Master Fund, and HC, IN for David Kroin.