[6-K] Cosan S.A. Current Report (Foreign Issuer)

Rhea-AI Filing Summary

Cosan S.A. reported that Brazil’s antitrust authority CADE approved without restrictions the planned subscription of newly issued Cosan shares by funds affiliated with Perfin and BTG Pactual (collectively, the “Investors”). The company noted that any subscription by the Investors under the Investment Agreement depends on the conclusion and allocation in the first public offering currently in progress.

Cosan stated that CADE’s decision is pending the expiration of a legal period of 15 days. The company added that the closing of the Bookbuilding Procedure for the first public offering is expected to occur on November 3, 2025, pursuant to Brazilian securities regulations. Cosan will keep shareholders informed through official channels.

Insights

LatAm regulatory and capital markets analyst

CADE clearance enables potential investor share subscription, pending offering steps.

Cosan received CADE approval “without restrictions” for the Investors to subscribe to newly issued shares, a key regulatory step that permits the contemplated structure to proceed. However, the Investment Agreement conditions any subscription on the conclusion and allocation of the first public offering.

The approval still awaits the lapse of a 15-day legal period before becoming fully effective under applicable rules. The company indicates the Bookbuilding Procedure for the first public offering is expected to close on November 3, 2025, which frames near-term sequencing.

Actual outcomes depend on completion and allocation of the offering and the expiration of the legal window. Subsequent disclosures may detail execution, allocation, and any implications once these milestones are met.

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 2025

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 19836

MATERIAL FACT

COSAN S.A. (B3: CSAN3; NYSE: CSAN) ("Cosan" or "Company"), in compliance with the provisions of CVM Resolution No. 44, of August 23, 2021, in the context of the Material Fact disclosed on September 21, 2025, hereby informs its shareholders and the market in general that the Conselho Administrativo de Defesa Econômica ("CADE") has approved without restrictions the subscription of shares issued by Cosan, by the funds Perfin Rally Fundo de Investimento em Participações Multiestratégia Responsabilidade Limitada, Classe Única BTG Pactual Infraestrutura III Fundo de Investimento em Participações Multiestratégia, and Classe Única Fundo de Investimento em Participações BPAC3 - Multiestratégia Responsabilidade Limitada (collectively, "Investors"). The eventual subscription of the shares by the Investors, under the terms of the Investment Agreement, depends on the conclusion and allocation in the first public offering in progress.

CADE's decision is still awaiting the expiration of the legal period of 15 days, under the terms of the applicable legislation.

The Company will keep its shareholders and the market informed about the conclusion of the first public offering, whose closing of the Bookbuilding Procedure is expected to take place on November 3, 2025, pursuant to the law and CVM regulations. More information may be obtained in due course on the CVM (www.gov.br/cvm) and the Company's Investor Relations (www.cosan.com.br) websites.

São Paulo, October 30, 2025.

Rodrigo Araujo Alves

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 30, 2025

	COSAN S.A.
	By:	/s/ Rodrigo Araujo Alves
		Name:            Rodrigo Araujo Alves
		Title: Chief Financial Officer

FAQ

What did CADE approve for Cosan (CSAN)?

CADE approved without restrictions the subscription of Cosan shares by the Investors under the Investment Agreement.

Who are the Investors mentioned by Cosan (CSAN)?

Funds affiliated with Perfin and BTG Pactual, including Perfin Rally FIP Multiestratégia and BTG Pactual Infraestrutura III FIP Multiestratégia, among others.

What conditions remain before the Investors can subscribe Cosan shares?

The eventual subscription depends on the conclusion and allocation in the first public offering in progress.

Is the CADE decision immediately effective for Cosan (CSAN)?

The decision awaits the expiration of a legal period of 15 days under applicable legislation.

When is Cosan’s bookbuilding expected to close?

The closing of the Bookbuilding Procedure is expected on November 3, 2025.

Where can investors find further information from Cosan (CSAN)?

Updates will be available on the CVM website (www.gov.br/cvm) and Cosan’s Investor Relations site (www.cosan.com.br).