[SCHEDULE 13G] Perimeter Acquisition Corp. I Warrant SEC Filing

Rhea-AI Filing Summary

Healthcare of Ontario Pension Plan Trust Fund (HOOPP) reported beneficial ownership of 1,500,000 Class A ordinary shares of Perimeter Acquisition Corp. I, representing 6.1% of the outstanding Class A shares based on the issuer's reported 24,788,000 shares outstanding. The position is held in the form of units that include one Class A share and one-half of a redeemable warrant; whole warrants allow purchase of a Class A share at $11.50 per share.

HOOPP identifies itself as a pension plan trust fund organized in Ontario, Canada and certifies the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of the issuer.

Positive

• HOOPP holds a material stake of 1,500,000 Class A shares representing 6.1% of the outstanding Class A shares
• Position includes warrants (units include one Class A share and one-half of a redeemable warrant; whole warrants exercisable at $11.50), relevant for dilution analysis

Negative

• None.

Insights

Securities Analyst

TL;DR: Institutional stake of 6.1% in a SPAC-like issuer is material disclosure but the filer disclaims intent to influence control.

The filing shows HOOPP holds 1.5 million Class A shares (units) representing a >5% stake, which is a material ownership threshold triggering public disclosure. For investors, a single institutional holder at this size can affect perceived support or liquidity for the issuer's securities, yet the filer explicitly states the position is held in the ordinary course and not for control purposes. The inclusion of warrants (one-half per unit; whole warrant exercise price $11.50) is important for potential future dilution analysis. Overall impact: impactful (disclosure-level) but neutral on governance intent.

Corporate Governance Expert

TL;DR: A 6.1% passive holding by a large pension fund is notable for monitoring, but the filer denies control intentions.

From a governance perspective, the holding crosses the 5% materiality threshold and merits attention to both voting influence and future coordination with other holders. However, the report classifies the reporting person as a pension plan trust fund and affirms acquisition and holding in the ordinary course, which signals no immediate activism or control campaign. Investors should note the stake size and the convertible economics via attached warrants when assessing potential dilution or voting dynamics. Impact rating: impactful disclosure; neutral governance signal.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Perimeter Acquisition Corp. I

(Name of Issuer)

Class A ordinary shares, $0.0001 par value

(Title of Class of Securities)

G7010A129

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. G7010A129

1

Names of Reporting Persons

Healthcare of Ontario Pension Plan Trust Fund

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

ONTARIO, CANADA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 1,500,000.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 1,500,000.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,500,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.1 %

12

Type of Reporting Person (See Instructions)

FI

Comment for Type of Reporting Person: In reference to Rows 5, 7 and 9 above, amount consists of Class A ordinary shares, $0.0001 par value ("Class A Shares"), of Perimeter Acquisition Corp. I, a blank check company formed under the laws of the Cayman Islands (the "Issuer"), that are held in the form of units, each consisting of one Class A Share and one-half of one redeemable warrant. Each whole warrant entitles the holder thereof to purchase one Class A Share at a price of $11.50 per share, subject to adjustment. In reference to Row 11 above, percentage ownership is based on 24,788,000 Class A Shares issued and outstanding as of June 18, 2025, as reported on the Issuer's quarterly report on Form 10-Q for the quarter ended on March 31, 2025, filed with the Securities and Exchange Commission on June 23, 2025.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Perimeter Acquisition Corp. I
(b)	Address of issuer's principal executive offices: 6060 N. Central Express Way, Suite 500, Dallas, Texas, 75204
Item 2.
(a)	Name of person filing: Healthcare of Ontario Pension Plan Trust Fund ("HOOPP")
(b)	Address or principal business office or, if none, residence: 1 York Street, Suite 1900, Toronto, Ontario, Canada, M5J 0B6
(c)	Citizenship: Ontario, Canada
(d)	Title of class of securities: Class A ordinary shares, $0.0001 par value
(e)	CUSIP No.: G7010A129
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
	A pension plan formed as a trust under the laws of Ontario, Canada and registered with the Financial Services Regulatory Authority of Ontario.
Item 4.	Ownership
(a)	Amount beneficially owned: See Item 9 on page 2.
(b)	Percent of class: See Item 11 on page 2.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Item 5 on page 2.
	(ii) Shared power to vote or to direct the vote: See Item 6 on page 2.
	(iii) Sole power to dispose or to direct the disposition of: See Item 7 on page 2.
	(iv) Shared power to dispose or to direct the disposition of: See Item 8 on page 2.
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. By signing below I certify that, to the best of my knowledge and belief, the regulatory scheme applicable to a pension plan formed as a trust under the laws of Ontario, Canada and registered with the Financial Services Regulatory Authority of Ontario is substantially comparable to the regulatory scheme applicable to the functionally equivalent U.S. institution(s). I also undertake to furnish to the Securities and Exchange Commission staff, upon request, information that would otherwise be disclosed in a Schedule 13D.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Healthcare of Ontario Pension Plan Trust Fund

Signature:	/s/ Abas Kanu
Name/Title:	VP, HOOPP Compliance Officer
Date:	08/13/2025

FAQ

How many Perimeter Acquisition Corp. I (PMTRW) shares does HOOPP own?

HOOPP beneficially owns 1,500,000 Class A ordinary shares (held in unit form).

What percentage of PMTRW does HOOPP's stake represent?

The position represents 6.1% of the Class A shares based on the issuer's reported 24,788,000 Class A shares outstanding.

Are there warrants associated with HOOPP's holdings in PMTRW?

Yes. The shares are held in units that include one Class A share and one-half of one redeemable warrant; whole warrants permit purchase of a Class A share at $11.50.

Does HOOPP intend to influence control of Perimeter Acquisition Corp. I?

HOOPP certifies the securities are held in the ordinary course of business and were not acquired to change or influence control of the issuer.

What type of entity is the reporting person HOOPP?

The reporting person is the Healthcare of Ontario Pension Plan Trust Fund, a pension plan formed as a trust under the laws of Ontario, Canada.