Business Context and Reporting Period
This Form 6-K filing by Companhia de Saneamento Básico do Estado de São Paulo (SABESP) and Empresa Metropolitana de Águas e Energia S.A. (EMAE) reports a Joint Material Fact regarding the approval of a merger of shares. The filing date is September 18, 2026, covering events occurring in September 2026. The document details the consummation of the merger of all EMAE shares not held by SABESP into SABESP, following shareholder approvals at Extraordinary Shareholders' Meetings held on July 30, 2026 (SABESP) and September 16, 2026 (EMAE).
Key Financial Metrics
The filing does not provide standard financial performance metrics such as revenue, profit, cash flow, margins, debt, or liquidity for the reporting period. The only specific financial values disclosed relate to the merger transaction:
- Exchange Ratio: 1.31950000000 SABESP common shares for each 1 EMAE common or preferred share.
- Withdrawal Right Reimbursement Value: R$ 18.18 per EMAE share (based on book value as of June 30, 2026).
- Alternative Book Value: R$ 16.09 per share (based on the December 31, 2025 balance sheet).
Material Changes
The primary material change is the structural consolidation of EMAE into SABESP. Key changes include:
- Shareholder Base Transfer: EMAE shareholders (excluding SABESP) will receive SABESP shares, effectively transferring the EMAE shareholder base to SABESP.
- Bookkeeping Agent Change: EMAE's bookkeeping services are migrating from BTG Pactual to Itaú Corretora de Valores S.A., effective October 1, 2026.
- Share Delisting: EMAE shares will cease trading on B3 following the merger consummation.
Guidance, Outlook, and Risks
Management Commentary and Timetable: The companies provided an estimated timetable for the merger. The period for exercising withdrawal rights runs from September 18, 2026, to October 19, 2026. Fractional SABESP shares resulting from the exchange ratio will be sold on the spot market, with proceeds distributed to shareholders. Payment of reimbursement amounts to dissenting shareholders will occur after the withdrawal period expires.
Risks and Contingencies:
- Withdrawal Rights: Dissenting EMAE shareholders may exercise withdrawal rights to receive cash reimbursement at the book value of R$ 18.18 per share. SABESP shareholders do not have withdrawal rights due to sufficient market liquidity.
- Tax Implications: Non-resident investors (NRIs) are subject to Withholding Income Tax (WHT) on capital gains. Rates range from 15% to 25% depending on investor classification and tax residency. Failure to provide acquisition cost data by October 19, 2026, will result in the acquisition cost being deemed zero, maximizing tax liability.
- Reconsideration: EMAE management retains the right to call a General Shareholders' Meeting to reconsider the merger resolution within 10 days after the withdrawal period ends, depending on the volume of withdrawal rights exercised.
Investor Verification Checklist
- Verify the exact number of SABESP shares to be credited based on the 1.3195 exchange ratio and the handling of fractional shares.
- Confirm the deadline of October 19, 2026, for exercising withdrawal rights and submitting tax documentation for non-resident investors.
- Review the specific tax treatment applicable to your jurisdiction, particularly the WHT rates (15% to 25%) for non-resident investors.
- Monitor the announcement regarding the final date of EMAE share trading on B3 and the subsequent credit of SABESP shares.
- Check for any subsequent Material Facts regarding the volume of withdrawal rights exercised and whether the merger will be reconsidered.