1RT Acquisition Corp. — Linden Capital L.P. and affiliated filers reported beneficial ownership of Class A ordinary shares as of March 5, 2026. Linden Advisors and Siu Min (Joe) Wong each may be deemed beneficial owners of 1,010,100 Shares (approximately 5.9% of outstanding). Linden Capital and Linden GP LLC may be deemed beneficial owners of 973,096 Shares (approximately 5.6% of outstanding). The reported holdings consist of 973,096 Shares held by Linden Capital and 37,004 Shares held by managed accounts.
Positive
None.
Negative
None.
Insights
Filing reports passive beneficial ownership by an investment manager group.
The schedule identifies Linden Capital, Linden GP, Linden Advisors and Siu Min Wong as related reporting persons and attributes shared voting and dispositive power over the disclosed shares. The filing ties the 973,096 Shares to Linden Capital and notes 37,004 Shares in managed accounts as of March 5, 2026.
Ownership percentages are stated as ~5.9% (Linden Advisors, Mr. Wong) and ~5.6% (Linden Capital, Linden GP). Regulatory implications are routine for Schedule 13G reporting; subsequent filings would show material changes.
Positions are modest minority stakes without sole voting control.
The group reports only shared voting and dispositive power; no sole voting or sole dispositive power is claimed. The holdings are disclosed as managed accounts plus the partnership position, indicating pooled investment exposure rather than individual control.
Materiality is limited given the ~5–6% scale; changes to these positions would be visible in later ownership disclosures.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
1RT Acquisition Corp.
(Name of Issuer)
Class A ordinary shares, par value $0.0001 per share
(Title of Class of Securities)
03/05/2026
(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 Number(s):
1
Names of Reporting Persons
Linden Capital L.P.
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
BERMUDA
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
973,096.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
973,096.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
973,096.00
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)
5.6 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
1
Names of Reporting Persons
Linden GP LLC
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
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
973,096.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
973,096.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
973,096.00
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)
5.6 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
CUSIP Number(s):
1
Names of Reporting Persons
Linden Advisors LP
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
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,010,100.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,010,100.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,010,100.00
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)
5.9 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
1
Names of Reporting Persons
Siu Min Wong
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
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,010,100.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,010,100.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,010,100.00
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)
5.9 %
12
Type of Reporting Person (See Instructions)
IN, HC
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
1RT Acquisition Corp.
(b)
Address of issuer's principal executive offices:
205 West 28th Street, 2nd Floor Suite C, New York, NY 10001
Item 2.
(a)
Name of person filing:
This Statement is filed on behalf of each of the following persons (collectively, the "Reporting Persons")
i) Linden Capital L.P., a Bermuda limited partnership ("Linden Capital");
ii) Linden GP LLC, a Delaware limited liability company ("Linden GP");
iii) Linden Advisors LP, a Delaware limited partnership ("Linden Advisors"); and
iv) Siu Min (Joe) Wong ("Mr. Wong").
This Statement relates to Class A ordinary shares, par value $0.0001 per share (the "Shares") of 1RT Acquisition Corp. (the "Issuer") held for the account of Linden Capital and one or more separately managed accounts (the "Managed Accounts"). Linden GP is the general partner of Linden Capital and, in such capacity, may be deemed to beneficially own the Shares held by Linden Capital. Linden Advisors is the investment manager of Linden Capital and trading advisor or investment advisor for the Managed Accounts. Mr. Wong is the principal owner and controlling person of Linden Advisors and Linden GP. In such capacities, Linden Advisors and Mr. Wong may each be deemed to beneficially own the Shares held by Linden Capital and the Managed Accounts.
(b)
Address or principal business office or, if none, residence:
The principal business address for Linden Capital is Victoria Place, 31 Victoria Street, Hamilton HM10, Bermuda. The principal business address for each of Linden Advisors, Linden GP and Mr. Wong is 590 Madison Avenue, 32nd Floor, New York, New York 10022.
(c)
Citizenship:
i) Linden Capital is a Bermuda limited partnership.
ii) Linden GP is a Delaware limited liability company.
iii) Linden Advisors is a Delaware limited partnership.
iv) Mr. Wong is a citizen of China (Hong Kong) and the United States.
(d)
Title of class of securities:
Class A ordinary shares, par value $0.0001 per share
(e)
CUSIP No.:
G6757R105
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).
Item 4.
Ownership
(a)
Amount beneficially owned:
As of March 5, 2026, each of Linden Advisors and Mr. Wong may be deemed the beneficial owner of 1,010,100 Shares. This amount consists of 973,096 Shares held by Linden Capital and 37,004 Shares held by the Managed Accounts. As of March 5, 2026 each of Linden GP and Linden Capital may be deemed the beneficial owner of the 973,096 Shares held by Linden Capital.
(b)
Percent of class:
As of March 5, 2026 each of Linden Advisors and Mr. Wong may be deemed the beneficial owner of approximately 5.9% of Shares outstanding, and each of Linden GP and Linden Capital may be deemed the beneficial owner of approximately 5.6% of Shares outstanding.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Linden Capital and Linden GP: 0
Linden Advisors and Mr. Wong: 0
(ii) Shared power to vote or to direct the vote:
Linden Capital and Linden GP: 973,096
Linden Advisors and Mr. Wong: 1,010,100
(iii) Sole power to dispose or to direct the disposition of:
Linden Capital and Linden GP: 0
Linden Advisors and Mr. Wong: 0
(iv) Shared power to dispose or to direct the disposition of:
Linden Capital and Linden GP: 973,096
Linden Advisors and Mr. Wong: 1,010,100
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
See disclosure in Items 2 and 4 hereof.
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
See disclosure in Item 2 hereof.
Item 8.
Identification and Classification of Members of the Group.
If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(K), so indicate under Item 3(k) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group.
See Exhibit A attached hereto.
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 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.
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.
Linden Capital L.P.
Signature:
/S/ Saul Ahn
Name/Title:
Saul Ahn, Authorized Signatory
Date:
03/12/2026
Linden GP LLC
Signature:
/S/ Saul Ahn
Name/Title:
Saul Ahn, Authorized Signatory
Date:
03/12/2026
Linden Advisors LP
Signature:
/S/ Saul Ahn
Name/Title:
Saul Ahn, General Counsel
Date:
03/12/2026
Siu Min Wong
Signature:
/S/ Saul Ahn
Name/Title:
Saul Ahn, Attorney-in-Fact for Siu Min Wong**
Date:
03/12/2026
Comments accompanying signature: **Duly authorized under Siu Min Wong's Power of Attorney, dated June 10, 2019, incorporated herein by reference to Exhibit B of the statement on Schedule 13G filed by Linden Capital L.P. on June 19, 2019 in respect of its holdings in Haymaker Acquisition Corp II.
What stake does Linden Advisors report in 1RT Acquisition Corp. (ONCH)?
Linden Advisors reports beneficial ownership of 1,010,100 Shares, equal to approximately 5.9% of the class as of March 5, 2026. This total includes 973,096 Shares held by Linden Capital and 37,004 Shares in managed accounts.
How many shares does Linden Capital directly hold in ONCH?
Linden Capital directly holds 973,096 Shares of Class A ordinary shares as of March 5, 2026, which the filing reports as approximately 5.6% of the outstanding class.
Does the filing show sole voting control by the Linden group in ONCH?
No. The filing states the group has 0 shares with sole voting power and reports only shared voting power of 973,096 or 1,010,100 depending on the reporting person, as of March 5, 2026
Who are the reporting persons named in the Schedule 13G for ONCH?
The reporting persons are Linden Capital L.P., Linden GP LLC, Linden Advisors, and Siu Min (Joe) Wong. Addresses and organizational citizenship are included in the filing text.
