MBX Rule 144: Sales by Richard B. Bartram, Fidelity 5,000

MBX Rule 144 notice lists proposed and recent resale activity in Common shares.

Rhea-AI Filing Summary

MBX Rule 144 notice lists proposed and recent resale activity in Common shares. The excerpt shows a broker entry for Fidelity Brokerage Services LLC with 5000 shares and an amount field 159000.00 dated 05/01/2026. It also documents three reported sales by Richard B. Bartram: 10,000 shares on 03/16/2026 for $300,471.00, 1,061 shares on 03/25/2026 for $30,217.49, and 10,423 shares on 04/22/2026 for $341,377.72.

Key Figures

Fidelity entry - shares: 5000 Fidelity entry - amount: 159000.00 Sale by Richard B. Bartram: 10,000 shares +2 more

5 metrics

Fidelity entry - shares 5000 Fidelity Brokerage Services LLC line dated 05/01/2026

Fidelity entry - amount 159000.00 Associated amount on Fidelity line dated 05/01/2026

Sale by Richard B. Bartram 10,000 shares Sale dated 03/16/2026 for $300,471.00

Sale by Richard B. Bartram 1,061 shares Sale dated 03/25/2026 for $30,217.49

Sale by Richard B. Bartram 10,423 shares Sale dated 04/22/2026 for $341,377.72

Key Terms

Rule 144 / Form 144, Options Granted, Cash Common

3 terms

Rule 144 / Form 144 regulatory

"144: Securities To Be Sold"

Options Granted financial

"Options Granted - 04/20/2022"

Cash Common financial

"05/01/2026 | Cash Common"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does MBX's Form 144 show about shares offered by Fidelity?

It shows a Fidelity entry listing 5000 shares with an associated amount of 159000.00 dated 05/01/2026. This line appears under "Securities To Be Sold" alongside the market identifier NASDAQ.

How many shares did Richard B. Bartram report selling in the excerpt?

The excerpt lists three sales totaling 21,484 shares across three dates in 2026. The sales are dated 03/16, 03/25, and 04/22 with per-line amounts provided.

What dollar amounts are shown for Bartram's reported sales?

The filing shows proceeds of $300,471.00, $30,217.49, and $341,377.72 for the three reported sales. Each amount is listed on the same line as the corresponding sale date and share count.

Are the sales tied to option exercises in this excerpt?

The excerpt includes "Options Granted" notes dated 04/20/2022 and 11/07/2022 and lists quantities of 2,500 each, suggesting option-origin lines appear in the table. The filing text pairs those option grant dates with 05/01/2026 entries.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/01/2026 - 02:59 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001723729
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	MBX Biosciences, Inc.
SEC File Number	001-42272
Address of Issuer	11711 N. MERIDIAN STREET SUITE 300 CARMEL INDIANA 46032
Phone	3179893100
Name of Person for Whose Account the Securities are To Be Sold	Bartram Richard
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Former Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917	5000	159000.00	47510243	05/01/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	05/01/2026	Options Granted - 04/20/2022	Issuer			2500	05/01/2026	Cash
Common	05/01/2026	Options Granted - 11/07/2022	Issuer			2500	05/01/2026	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Richard B. Bartram 11711 N. Meridian Street Suite 300 Carmel IN 46032	Common	03/16/2026	10000	300471.00
Richard B. Bartram 11711 N. Meridian Street Suite 300 Carmel IN 46032	Common	03/25/2026	1061	30217.49
Richard B. Bartram 11711 N. Meridian Street Suite 300 Carmel IN 46032	Common	04/22/2026	10423	341377.72

144: Remarks and Signature

Remarks
Date of Notice	05/01/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Adam Gehring, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Richard B. Bartram
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)