Korsana Biosciences director plans sale of 2,139 shares

Korsana Biosciences, Inc. (CYCN) director Errol B. De Souza has filed a notice of proposed sale under Rule 144 for 2,139 shares of common stock of the company, to be handled through Morgan Stanley Smith Barney LLC on NASDAQ.

Rhea-AI Filing Summary

Korsana Biosciences, Inc. (CYCN) director Errol B. De Souza has filed a notice of proposed sale under Rule 144 for 2,139 shares of common stock of the company, to be handled through Morgan Stanley Smith Barney LLC on NASDAQ.

The shares relate to restricted stock that vested between November 30, 2023 and September 1, 2024, and the filing lists an approximate aggregate market value of $74,843.61 for the securities covered by this notice as of September 18, 2026.

Key Figures

Shares proposed for sale: 2,139 shares Approximate aggregate market value: $74,843.61 Date of Notice: September 18, 2026 +1 more

4 metrics

Shares proposed for sale 2,139 shares Common stock covered by the Rule 144 notice for Korsana Biosciences, Inc.

Approximate aggregate market value $74,843.61 Value associated with the 2,139 shares of common stock as of September 18, 2026

Date of Notice September 18, 2026 Filing date of the Rule 144 notice by director Errol B. De Souza

Vesting period for restricted stock November 30, 2023 to September 1, 2024 Period during which the restricted stock underlying the 2,139 shares vested

Key Terms

Rule 144, restricted stock, aggregate market value, common stock

4 terms

Rule 144 regulatory

"filed a notice of proposed sale under Rule 144 for 2,139 shares"

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.

restricted stock financial

"The securities to be sold were acquired upon the 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.

aggregate market value financial

"lists an approximate aggregate market value of $74,843.61 for the securities"

Aggregate market value is the combined price you would pay to buy all outstanding shares of a company or all companies in a group at current market prices — essentially the sum of each stock’s market capitalization. It matters to investors because it shows the overall size and weight of an investment or sector (like the total cost to buy every piece of a puzzle), helps compare scale across companies or markets, and influences index composition and risk exposure.

common stock financial

"2,139 shares of common stock of the company"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

FAQ

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

What did Korsana Biosciences (CYCN) disclose in this Form 144 filing?

A director, Errol B. De Souza, filed a Rule 144 notice covering the proposed sale of 2,139 shares of Korsana Biosciences common stock through Morgan Stanley Smith Barney LLC on NASDAQ.

How many CYCN shares are covered by the director’s planned Rule 144 sale?

The Form 144 covers a proposed sale of 2,139 shares of Korsana Biosciences, Inc. common stock under Rule 144.

What is the approximate market value of the CYCN shares in this Form 144?

The notice lists an approximate aggregate market value of $74,843.61 for the 2,139 shares of Korsana Biosciences common stock covered by this proposed Rule 144 sale.

What type of CYCN securities are being proposed for sale and how were they acquired?

The securities are restricted shares of common stock of Korsana Biosciences, Inc., which the director states were acquired upon the vesting of restricted stock during the period from November 30, 2023 through September 1, 2024.

When was the Rule 144 notice for CYCN filed and what is the listed sale date?

The Date of Notice is September 18, 2026, and that same date, September 18, 2026, is listed as the relevant date for the 2,139 shares and their $74,843.61 aggregate market value.

Who is the broker handling the proposed CYCN share sale under Rule 144?

The proposed sale of 2,139 CYCN common shares is listed as being handled through Morgan Stanley Smith Barney LLC Executive Financial Services at 1 New York Plaza on NASDAQ.

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

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Available on EDGAR 09/18/2026 - 04:50 PM Accepted by SEC EDGAR 09/18/2026 - 04:49 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	2139	74843.61	45541000	09/18/2026	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	11/30/2023	Restricted Stock	Issuer			2139	11/30/2023	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

Nothing to Report

144: Remarks and Signature

Remarks	The securities to be sold were acquired upon the vesting of restricted stock during the period of 11/30/2023 through 09/01/2024
Date of Notice	09/18/2026
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)