Large insider buys add 971K Cartesian Growth Corp III (CGCT) shares

Rhea-AI Filing Summary

Cartesian Growth Corp III saw significant insider buying in its Class A shares. On April 1, 2026, an entity associated with Chairman and CEO Peter Yu purchased 671,000 Class A ordinary shares at $10.299 per share. On March 31, 2026, a related open-market purchase added 300,000 Class A ordinary shares at $10.277 per share, bringing total recent purchases to 971,000 shares.

The Class A shares are held by Pangaea Three-B, LP, which is controlled by Peter Yu; both Pangaea and Yu disclaim beneficial ownership except for their pecuniary interests. Sponsor-related entities also hold 6,800,000 Class B ordinary shares directly and 100,000 Class B ordinary shares indirectly, which automatically convert into Class A shares on a one-for-one basis at no cost in connection with the initial business combination.

Insights

Insider trading and SPAC structure analyst

Large sponsor-affiliated open-market buying adds 971,000 Class A shares while substantial founder Class B stake remains.

Entities associated with Peter Yu, Chairman and CEO of Cartesian Growth Corp III, executed two open-market purchases totaling 971,000 Class A ordinary shares at prices around $10.28–$10.30. These transactions are active buys, not option exercises or tax events.

The filing also shows sponsor-related holdings of 6,800,000 Class B ordinary shares directly and 100,000 Class B ordinary shares indirectly, each convertible one-for-one into Class A at an exercise price of $0.0000. This highlights a sizable founder position that will convert around the initial business combination, though the exact impact depends on overall share count and future transaction terms.

Because the purchases occur alongside a large existing founder stake and no earnings or guidance figures, the information is notable but not clearly transformative on its own. Subsequent company communications around the initial business combination may further clarify how these positions affect future ownership structure.

Insider Trade Summary

Net Buyer: 971,000 shares ($9,993,729)

Net Buy 4 txns

Insider CGC III Sponsor LLC, Yu Peter

Role 10% Owner | Chairman and CEO

Bought 971,000 shs ($9.99M)

Type	Security	Shares	Price	Value
Purchase	Class A ordinary shares	671,000	$10.299	$6.91M
Purchase	Class A ordinary shares	300,000	$10.277	$3.08M
holding	Class B ordinary shares	--	--	--
holding	Class B ordinary shares	--	--	--

Holdings After Transaction: Class A ordinary shares — 971,000 shares (Direct); Class B ordinary shares — 6,800,000 shares (Direct); Class B ordinary shares — 100,000 shares (Indirect, See footnote)

Footnotes (1)

1. Represents Class A ordinary shares of Cartesian Growth Corporation III (the "Issuer") held directly by Pangaea Three-B, LP ("Pangaea"). Pangaea is controlled by Peter Yu. Consequently, Mr. Yu may be deemed to share voting and dispositive control over the securities held by Pangaea, 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. The Class B ordinary shares of 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"). Represents 6,800,000 Class B ordinary shares held directly by the Sponsor and 100,000 Class B ordinary 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 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.

Key Figures

Open-market purchase 1: 671,000 Class A shares at $10.299 Open-market purchase 2: 300,000 Class A shares at $10.277 Total recent Class A purchases: 971,000 Class A shares +4 more

7 metrics

Open-market purchase 1 671,000 Class A shares at $10.299 Transaction dated April 1, 2026

Open-market purchase 2 300,000 Class A shares at $10.277 Transaction dated March 31, 2026

Total recent Class A purchases 971,000 Class A shares Net buy shares in transaction summary

Direct Class A holding after purchase 971,000 Class A shares Total shares following April 1, 2026 transaction

Direct Class B founder shares 6,800,000 Class B shares Convertible into Class A on a one-for-one basis

Indirect Class B founder shares 100,000 Class B shares Held by DirectorCo; 90,000 for independent directors

Class B exercise price $0.0000 Conversion price for Class B into Class A shares

Key Terms

Class A ordinary shares, Class B ordinary shares, initial business combination, beneficial ownership, +2 more

6 terms

Class A ordinary shares financial

"On April 1, 2026, an entity associated with Peter Yu purchased 671,000 Class A ordinary shares at $10.299 per share."

Class A ordinary shares are a type of ownership stake in a company that typically grants voting rights to shareholders, allowing them to have a say in important company decisions. They often come with priority in receiving dividends or profits, making them attractive to investors seeking influence and potential income. These shares help distinguish different levels of ownership and rights within a company's stock structure.

Class B ordinary shares financial

"Sponsor-related entities also hold 6,800,000 Class B ordinary shares directly and 100,000 Class B ordinary shares indirectly."

Class B ordinary shares are a type of ownership stake in a company that typically come with different voting rights or privileges compared to other share classes. For investors, they represent a way to hold part of the company’s value and influence its decisions, often with fewer voting rights than Class A shares. Understanding these shares helps investors assess their level of control and potential returns within a company.

initial business combination financial

"Class B ordinary shares will automatically convert into Class A ordinary shares concurrently with or immediately following the consummation of the Issuer's initial business combination."

An initial business combination is the deal in which a special-purpose acquisition company (SPAC) merges with or acquires an operating business to bring that business onto public markets. Think of the SPAC as an empty shell that raises money from investors, then uses that cash to buy a private company—this transaction turns the private company into a public one and often changes its ownership, valuation, and access to capital, so investors should watch for shifts in risk, future growth prospects, and shareholder rights.

beneficial ownership financial

"Pangaea and Mr. Yu may be deemed to share voting and dispositive control, and thus to share beneficial ownership of such securities."

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"Each of Pangaea and Mr. Yu disclaims beneficial ownership of such securities except to the extent of its or his pecuniary interest therein."

open-market purchase financial

"The transactions are coded as P and described as an open-market purchase of Class A ordinary shares."

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

Form 4 Insider Transactions: What Each Field Means →

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^*

CGC III Sponsor LLC

(Last) (First) (Middle)

505 FIFTH AVENUE, 15TH FLOOR

(Street)

NEW YORK NEW YORK 10017

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/31/2026

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

	Form filed by One Reporting Person
X	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
Class A ordinary shares	03/31/2026		P		300,000	A	$10.277	300,000	D(1)
Class A ordinary shares	04/01/2026		P	V	671,000	A	$10.299	971,000	D(1)

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
Class B ordinary shares	(2)							(2)	(2)	Class A ordinary shares	6,800,000		6,800,000	D(3)
Class B ordinary shares	(2)							(2)	(2)	Class A ordinary shares	100,000		100,000	I	See footnote(3)

1. Name and Address of Reporting Person^*

CGC III Sponsor LLC

(Last) (First) (Middle)

505 FIFTH AVENUE, 15TH FLOOR

(Street)

NEW YORK NEW YORK 10017

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Yu Peter

(Last) (First) (Middle)

505 FIFTH AVENUE, 15TH FLOOR

(Street)

NEW YORK NEW YORK 10017

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
X	Officer (give title below)		Other (specify below)
	Chairman and CEO

Explanation of Responses:

1. Represents Class A ordinary shares of Cartesian Growth Corporation III (the "Issuer") held directly by Pangaea Three-B, LP ("Pangaea"). Pangaea is controlled by Peter Yu. Consequently, Mr. Yu may be deemed to share voting and dispositive control over the securities held by Pangaea, 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.

2. The Class B ordinary shares of 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").

3. Represents 6,800,000 Class B ordinary shares held directly by the Sponsor and 100,000 Class B ordinary 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 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.

	/s/ Thomas Martin, Attorney-in-Fact	04/02/2026
	** 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)

FAQ

What insider transactions were reported for Cartesian Growth Corp III (CGCT)?

The filing shows entities associated with Chairman and CEO Peter Yu made two open-market purchases of Cartesian Growth Corp III Class A ordinary shares, totaling 971,000 shares. These buys occurred on March 31, 2026 and April 1, 2026 at prices slightly above $10 per share.

How many CGCT Class A shares were bought and at what prices?

Sponsor-affiliated entities purchased 671,000 Class A shares at $10.299 per share and 300,000 Class A shares at $10.277 per share. Together, these open-market transactions total 971,000 shares acquired in Cartesian Growth Corp III.

Who holds the newly acquired Cartesian Growth Corp III Class A shares?

The Class A shares are held directly by Pangaea Three-B, LP, which is controlled by Peter Yu. The filing states Pangaea and Yu may be deemed to share voting and dispositive power, while each disclaims beneficial ownership beyond their pecuniary interest in the securities.

What are the Class B ordinary shares mentioned for CGCT and how do they convert?

CGCT’s Class B ordinary shares automatically convert into Class A ordinary shares on a one-for-one basis, with an exercise price of $0.0000. Conversion occurs concurrently with or after the initial business combination, or earlier at the holder’s option, as described in the company’s Form S-1 registration statement.

How many Class B founder shares are held by sponsor-related entities of CGCT?

Sponsor-related entities hold 6,800,000 Class B ordinary shares directly and 100,000 Class B ordinary shares indirectly. Of the 100,000 indirectly held shares, 90,000 are held for the benefit of independent directors. All these Class B shares are convertible into Class A shares one-for-one.

What does this Form 4 suggest about insider alignment at Cartesian Growth Corp III (CGCT)?

The Form 4 shows significant open-market purchases of 971,000 Class A shares plus large existing holdings of convertible Class B shares by sponsor-related entities. This indicates meaningful financial exposure to CGCT’s equity structure, though the filing does not provide performance metrics or forward guidance.