Korsana Biosciences Director Proposes Sale of 4,903 Shares

The director also reported sales of 100 common shares on September 22 and 2,139 common shares on September 18, 2026.

Rhea-AI Filing Summary

Korsana Biosciences, Inc. (KRSA) director Errol B. De Souza reported a proposed sale of 4,903 common shares through Morgan Stanley Smith Barney LLC, with an aggregate market value of $171,555.97 and an approximate sale date of September 23, 2026. The shares were acquired upon vesting of restricted stock between October 1, 2024, and July 16, 2026.

Key Figures

Common shares proposed for sale: 4,903 shares Aggregate market value: $171,555.97 Common shares sold: 100 shares +3 more

6 metrics

Common shares proposed for sale 4,903 shares Approximate sale date September 23, 2026

Aggregate market value $171,555.97 Proposed sale

Common shares sold 100 shares September 22, 2026

Reported sale value $3,499.00 Sale on September 22, 2026

Common shares sold 2,139 shares September 18, 2026

Reported sale value $74,843.61 Sale on September 18, 2026

Key Terms

Restricted Stock, Rule 144

2 terms

Restricted Stock financial

"vesting of restricted stock"

Shares granted to an individual that carry limits on transfer or sale until certain conditions are met, such as staying with the company for a set time or hitting performance targets. Think of them as a locked gift that gradually opens; for investors they matter because they affect how many shares may enter the market later, signal management incentives and potential dilution, and reveal confidence in future company performance.

Rule 144 regulatory

"definition of "person" in paragraph (a) of Rule 144"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

FAQ

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

How many KRSA shares is director Errol B. De Souza proposing to sell?

Errol B. De Souza reported a proposed sale of 4,903 common shares, with an aggregate market value of $171,555.97 and an approximate sale date of September 23, 2026, through Morgan Stanley Smith Barney LLC.

What KRSA shares did its director sell in the past three months?

Errol B. De Souza reported selling 100 common shares on September 22, 2026, for $3,499.00, and 2,139 common shares on September 18, 2026, for $74,843.61.

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

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Available on EDGAR 09/23/2026 - 04:50 PM Accepted by SEC EDGAR 09/23/2026 - 04:50 PM 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	0001213895
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	KORSANA BIOSCIENCES, INC.
SEC File Number	001-38787
Address of Issuer	203 Crescent Street, Bldgs. #3/3A/4, Suite 503, Waltham MASSACHUSETTS 02453
Phone	(781) 516-2325
Name of Person for Whose Account the Securities are To Be Sold	ERROL B DE SOUZA
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	Director

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	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	4903	171555.97	45541425	09/23/2026	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	10/01/2024	Restricted Stock	Issuer			4903	10/01/2024	Not Applicable

* 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
ERROL B DE SOUZA 203 Crescent Street, Bldgs. #3/3A/4, Suite 503, Waltham MA 02453	Common	09/22/2026	100	3499.00
ERROL B DE SOUZA 203 Crescent Street, Bldgs. #3/3A/4, Suite 503, Waltham MA 02453	Common	09/18/2026	2139	74843.61

144: Remarks and Signature

Remarks	The securities to be sold were acquired upon the vesting of restricted stock during the period of 10/01/2024 through 07/16/26.
Date of Notice	09/23/2026
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/ Errol B Desouza
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)