Cosan's Rumo stake sale talks end exclusivity, no deal

Cosan says it continues to assess alternatives across its assets with a view to optimizing its capital structure.

Rhea-AI Filing Summary

Cosan S.A. (CSANY) said that, after receiving proposals for a potential sale of its equity interest in Rumo S.A., it engaged in exclusive negotiations with interested potential investors. The exclusivity period expired without an agreement Cosan deemed strategically and commercially appropriate for the sale of any portion of that interest. As of October 20, 2026, Cosan said it continues to evaluate alternatives across its assets with a view to optimizing its capital structure and will keep shareholders and the market informed in accordance with applicable regulations.

Key Terms

exclusive negotiations, equity interest, capital structure

3 terms

exclusive negotiations financial

"engaged in exclusive negotiations with potential investors"

equity interest financial

"potential sale of its equity interest in Rumo S.A."

An equity interest is an ownership stake in a company that gives the holder a share of its assets, profits and sometimes voting power—think of owning a slice of a pie that grows or shrinks with the business. Investors care because the size and type of that stake determine how much they benefit from future gains, bear losses, receive dividends, or influence decisions, and it directly affects the value and risk of their investment.

capital structure financial

"optimizing its capital structure"

Capital structure is the way a company finances its operations and growth by using different sources of money, such as borrowed funds (loans or bonds) and owner’s equity (investments from owners or shareholders). It’s like a recipe for baking a cake, where the balance of ingredients affects the final product's strength and taste; similarly, the mix of debt and equity influences a company's stability and risk. For investors, understanding a company's capital structure helps gauge how risky it might be to invest or lend money.

FAQ

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

Did Cosan (CSANY) agree to sell its Rumo stake?

No. Cosan said the exclusivity period expired without an agreement it deemed strategically and commercially appropriate for the sale of any portion of its equity interest in Rumo S.A.

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

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Available on EDGAR 10/21/2026 - 06:02 AM EDT Accepted by SEC EDGAR 10/20/2026 - 07:37 PM EDT Learn about SEC filing dates

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Issuer

Pursuant To Rule 13a-16 Or 15d-16 of the

Securities Exchange Act of 1934

For the month of October 2026

Commission File Number: 333-251238

COSAN S.A.

(Exact name of registrant as specified in its charter)

N/A

(Translation of registrant’s name into English)

Av. Brigadeiro Faria Lima, 4100, – 16th floor
São Paulo, SP 04538-132 Brazil
(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40‑F:  

Form 20-F ☒ Form 40-F ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes ☐ No ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes ☐ No ☒

 

COSAN S.A.

CNPJ nº 50.746.577/0001-15

NIRE 35.300.177.045

Publicly Held Company

CVM Code 01983-6

MATERIAL FACT

COSAN S.A. (B3: CSAN3; OTC Pink: CSANY) (the “Company” or “Cosan”), in compliance with Brazilian Securities and Exchange Commission (“CVM”) Resolution No. 44/2021 and further to the Notice to the Market disclosed on June 29, 2026, and the Material Fact disclosed on August 20, 2026, hereby informs its shareholders and the market in general that, in connection with the proposals received for a potential sale of its equity interest in Rumo S.A. (“Rumo”), the Company engaged in exclusive negotiations with potential investors interested in such equity interest. However, as of this date, the exclusivity period has expired without the Company reaching any agreement that it deemed strategically and commercially appropriate for the sale of any portion of its equity interest.

Cosan reiterates that it continues to evaluate alternatives across all of its assets with a view to optimizing its capital structure, while remaining committed to creating value for its shareholders in connection with any such potential transactions.

The Company will keep its shareholders and the market informed in accordance with applicable regulations.

São Paulo, October 20, 2026.

José Cezario Menezes de Barros Sobrinho

Chief Financial and Investor Relations Officer

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: October 20, 2026

	COSAN S.A.
	By:	/s/ José Cezario Menezes de Barros Sobrinho
		Name:            José Cezario Menezes de Barros Sobrinho
		Title: Chief Financial Officer