Sec Form 3 Filing - CGC III Sponsor LLC @ Cartesian Growth Corp III - 2025-05-01

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person CGC III Sponsor LLC 2. Issuer Name and Ticker or Trading Symbol Cartesian Growth Corp III [ CGCT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 505 FIFTH AVENUE, 15TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 05/01/2025 (Street) NEW YORK, NY10017 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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 Class B ordinary shares ( 1 ) ( 1 ) ( 1 ) Class A ordinary shares 6,800,000 ( 2 ) D ( 3 ) Class B ordinary shares ( 1 ) ( 1 ) ( 1 ) Class A ordinary shares 100,000 I See Footnote ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other CGC III Sponsor LLC 505 FIFTH AVENUE, 15TH FLOOR NEW YORK, NY10017 X Pangaea Three-B, LP 505 FIFTH AVENUE, 15TH FLOOR NEW YORK, NY10017 X Yu Peter 505 FIFTH AVENUE, 15TH FLOOR NEW YORK, NY10017 X X Chairman and CEO Signatures /s/ Adam Namoury, Attorney-in-Fact 05/01/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Class B ordinary shares of Cartesian Growth Corporation III (the "Issuer") have no expiration date and will automatically convert into Class A ordinary shares concurrently with or immediately following the consummation of the Issuer's initial business combination, or earlier at the option of the holder, on a one-for-one basis, subject to adjustment, as described in the Registration Statement on Form S-1 (File No. 333-284565) (the "Registration Statement") related to the Issuer's initial public offering (the "IPO"). ( 2 )Includes up to 900,000 shares subject to forfeiture by CGC III Sponsor LLC (the "Sponsor") depending on the extent to which the IPO underwriters' over-allotment option is exercised, as described in the Registration Statement. ( 3 )Represents 6,800,000 shares held directly by the Sponsor and 100,000 shares held directly by CGC III Sponsor DirectorCo LLC ("DirectorCo") (of which 90,000 shares are held by DirectorCo for the benefit of the Issuer's independent directors). The Sponsor is the sole managing member of DirectorCo. Pangaea Three-B, LP ("Pangaea") is the sole member of the Sponsor and is controlled by Peter Yu. Consequently, each of Pangaea and Mr. Yu may be deemed to share voting and dispositive control over the securities held by the Sponsor and DirectorCo, and thus to share beneficial ownership of such securities. Each of Pangaea and Mr. Yu disclaims beneficial ownership of such securities except to the extent of its or his pecuniary interest therein.

Remarks: See Exhibit 24.1 - Power of Attorney (CGC III Sponsor LLC); See Exhibit 24.2 - Power of Attorney (Pangaea Three-B, LP); See Exhibit 24.3 - Power of Attorney (Peter Yu)

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).

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