SABESP officer exercises RSUs, withholds shares for tax

COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP New Business & Projects Officer Rafael Costa Strauch reported compensation-related equity activity, not open-market trading.

Rhea-AI Filing Summary

COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP New Business & Projects Officer Rafael Costa Strauch reported compensation-related equity activity, not open-market trading. On May 1, 2026, he exercised 7,922 Restricted Stock Units (RSUs) into the same number of Common Shares at a stated price of $0.00 per share. To cover tax obligations, 2,179 Common Shares were disposed of through a tax-withholding transaction at $6.69 per share, leaving him with 5,743 Common Shares held directly. The RSUs come from a grant of 31,685 RSUs awarded on April 29, 2025, vesting in four equal annual installments through May 1, 2029, with 23,761 RSUs remaining after this vesting event.

Insider Trade Summary

7,922 shares exercised/converted

Exercise 3 txns

Insider Costa Strauch Rafael

Role New Bus. & Projects Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	7,922	$0.00	$0.00
Exercise	Common Shares	7,922	$0.00	$0.00
Exercise Price or Tax Liability	Common Shares	2,179	$6.69	$15K

Holdings After Transaction: Restricted Stock Units — 23,761 contracts (Direct); Common Shares — 5,743 shares (Direct)

Footnotes (1)

1. F1. On April 29, 2025, the reporting person was granted an aggregate of 31,685 restricted stock units ("RSUs"), vesting pro rata on each of May 1, 2026, May 1, 2027, May 1, 2028 and May 1, 2029, 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.

Key Figures

RSUs exercised: 7,922 shares Tax-withheld shares: 2,179 shares Share price for tax withholding: $6.69 per share +4 more

7 metrics

RSUs exercised 7,922 shares Restricted Stock Units converted to Common Shares on May 1, 2026

Tax-withheld shares 2,179 shares Common Shares delivered for tax obligations at $6.69 per share

Share price for tax withholding $6.69 per share Value used for 2,179-share tax-withholding disposition

Common Shares held after transactions 5,743 shares Direct ownership following May 1, 2026 Form 4 events

Original RSU grant 31,685 RSUs Grant dated April 29, 2025, vesting annually 2026–2029

Remaining RSUs 23,761 RSUs Outstanding after May 1, 2026 vesting event

RSU exercise price $0.00 per share Stated price for RSUs converted into Common Shares

Key Terms

Restricted Stock Units, tax-withholding disposition, derivative security, Common Shares

4 terms

Restricted Stock Units financial

"the reporting person was granted an aggregate of 31,685 restricted stock units ("RSUs"), vesting pro rata"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax-withholding disposition financial

"transaction_action": "tax-withholding disposition", "transaction_code_description": "Payment of exercise price or tax liability"

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

derivative security financial

""transaction_code_description": "Exercise or conversion of derivative security""

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

Common Shares financial

"Each RSU represents the contingent right to receive one Common Share of the Issuer upon vesting."

Common shares are the basic units of ownership in a company that give holders a claim on profits and a right to vote on key matters, like electing the board. Think of them as membership cards in a club: they let you share in successes and losses, but in a bankruptcy or liquidation they are paid after creditors and preferred shareholders, so their value can swing more and matters for assessing risk and potential return.

FAQ

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

What insider transactions did SABESP (SBS) officer Rafael Costa Strauch report?

Rafael Costa Strauch reported exercising 7,922 Restricted Stock Units into Common Shares and a related tax-withholding disposition of 2,179 Common Shares. These transactions are compensation-related and do not reflect open-market buying or selling activity by the officer.

How many SABESP (SBS) shares does Rafael Costa Strauch hold after this Form 4?

After these transactions, Rafael Costa Strauch directly holds 5,743 Common Shares. He also has 23,761 Restricted Stock Units outstanding, which represent a contingent right to receive additional Common Shares as they vest over future years.

What is the size and vesting schedule of Rafael Costa Strauch’s SABESP (SBS) RSU grant?

On April 29, 2025, Rafael Costa Strauch was granted 31,685 Restricted Stock Units. These RSUs vest pro rata on May 1 in 2026, 2027, 2028, and 2029, contingent on his continued service as an officer of SABESP during the vesting period.

What does the tax-withholding disposition mean in the SABESP (SBS) Form 4?

The tax-withholding disposition reflects 2,179 Common Shares delivered to satisfy tax obligations tied to RSU vesting. It is not an open-market sale, but a mechanism where shares are used to pay taxes triggered by the equity award’s exercise.

Did Rafael Costa Strauch buy or sell SABESP (SBS) shares on the open market?

The Form 4 does not show any open-market purchases or sales. It reports an RSU exercise that created 7,922 Common Shares and a related tax-withholding share disposition, both typical of equity compensation rather than discretionary market trading.

How many SABESP (SBS) RSUs remain after the May 1, 2026 vesting for Rafael Costa Strauch?

Following the May 1, 2026 RSU vesting and conversion, Rafael Costa Strauch has 23,761 Restricted Stock Units remaining from his 31,685-unit grant. These remaining RSUs are scheduled to vest in equal installments on May 1 of 2027, 2028, and 2029.

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

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Accepted by SEC EDGAR 05/15/2026 - 02:03 PM Learn about SEC filing dates

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Costa Strauch Rafael

(Last) (First) (Middle)

300 COSTA CARVALHO STREET

(Street)

SAO PAULO 05429-900

(City) (State) (Zip)

BRAZIL

(Country)

2. Issuer Name and Ticker or Trading Symbol
COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP [ SBSP3 ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	New Bus. & Projects Officer

2a. Foreign Trading Symbol
[SBS]

3. Date of Earliest Transaction (Month/Day/Year)
05/01/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Shares	05/01/2026		M		7,922	A	(1)	7,922	D
Common Shares	05/01/2026		F		2,179	D	$6.69	5,743	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(1)	05/01/2026		M			7,922	(1)	(1)	Common Shares	7,922	$0	23,761	D

Explanation of Responses:

1. On April 29, 2025, the reporting person was granted an aggregate of 31,685 restricted stock units ("RSUs"), vesting pro rata on each of May 1, 2026, May 1, 2027, May 1, 2028 and May 1, 2029, 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.

	/s/ Beatriz Caroline de Sousa Daher, as attorney-in-fact for Rafael Costa Strauch	05/15/2026
	** Signature of Reporting Person	Date
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.
* Form 4: SEC 1474 (03-26)