# EDGAR Filing Document

**Accession Number:** 0001170858
**File Stem:** 0001292814-26-003069
**Filing Date:** 2026-5
**Character Count:** 7078
**Document Hash:** 20386a28081ca6b3cb83cf697e52fd21
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001292814-26-003069.hdr.sgml**: 20260515

**ACCESSION NUMBER**: 0001292814-26-003069

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260501

**FILED AS OF DATE**: 20260515

**DATE AS OF CHANGE**: 20260515

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Leone Piani Carlos Augusto
- **CENTRAL INDEX KEY:** 0002119951

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-31317
- **FILM NUMBER:** 26985352

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 300 COSTA CARVALHO STREET
- **CITY:** SAO PAULO
- **PROVINCE COUNTRY:** D5
- **ZIP:** 05429-900
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP
- **CENTRAL INDEX KEY:** 0001170858
- **STANDARD INDUSTRIAL CLASSIFICATION:** WATER SUPPLY [4941]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 000000000
- **STATE OF INCORPORATION:** D5
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** RUA COSTA CARVALHO, 300
- **STREET 2:** SAO PAULO
- **CITY:** SP
- **PROVINCE COUNTRY:** D5
- **BUSINESS PHONE:** 55-11-3388-8110

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** RUA COSTA CARVALHO, 300
- **STREET 2:** SAO PAULO
- **CITY:** SP
- **PROVINCE COUNTRY:** D5

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Leone Piani Carlos Augusto<br><sub>(Last) (First) (Middle)</sub><br>300 COSTA CARVALHO STREET<br><sub>(Street)</sub><br>SAO PAULO, BRAZIL 05429-900<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-05-01 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_CEO_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP [ SBSP3 ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Shares | 2026-05-01 |  | M |  | 50295 | A | <sup>(1)</sup> | 64703 | D |  |
| Common Shares | 2026-05-01 |  | F |  | 13831 | D | $6.69 | 36464 | D |  |
| Common Shares |  |  |  |  |  |  |  | 14408 | I | Spouse |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Restricted Stock Units | <sup>(1)</sup> | 2026-05-01 |  | M |  |  | 50295 | <sup>(1)</sup> | <sup>(1)</sup> | Common Shares | 50295 | $0 | 955656 | D |  |

---

### Footnotes:

(1) On April 29, 2025, the reporting person was granted an aggregate of 1,005,951 restricted stock units ("RSUs"), vesting on May 1, 2026, May 1, 2027, May 1, 2028, May 1, 2029, May 1, 2030, May 1, 2031, May 1, 2032 and May 1, 2033, subject to continued service as an officer of the issuer. Each RSU represents the contingent right to receive one Common Share of the Issuer upon vesting.

**Remarks:**
All amounts reported in this Form 4 reflect certain recent events exempt from reporting under Section 16(a), namely (i) the receipt of rights to receive dividend equivalents (the accrual of which in this Form 4 upon vesting of the RSUs); (ii) the capital increase that occurred in March 2026; and (iii) the stock split approved by the Issuer's shareholders in April 2026.
Due to the issuer's status as a foreign private issuer pursuant to Rule 3a12-3(b) under the Securities Exchange Act of 1934 (the "Act"), the reporting person's transactions in the issuer's equity securities are exempt from Sections 16(b) and 16(c) of the Act.

**Signature:** /s/ Beatriz Caroline de Sousa Daher, as attorney-in-fact for Carlos Augusto Leone Piani  
**Date:** 2026-05-15

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**