Horizon Kinetics (MSB) reports 3.14M units, 23.9% stake (Schedule 13G/A)

Rhea-AI Filing Summary

Horizon Kinetics Asset Management LLC filed an amended Schedule 13G/A reporting beneficial ownership of 3,140,972 shares of Mesabi Trust Units of Beneficial Interest, representing 23.9% of the class as of 03/31/2026. The filing notes sole voting and dispositive power for the full amount and that Horizon Kinetics Holding Corp may be deemed to beneficially own those shares.

Key Figures

Beneficially owned: 3,140,972 shares Percent of class: 23.9% CUSIP: 590672101 +4 more

7 metrics

Beneficially owned 3,140,972 shares Units of Beneficial Interest, as of 03/31/2026

Percent of class 23.9% Percent of class reported on Schedule 13G/A

CUSIP 590672101 Mesabi Trust Units of Beneficial Interest

Sole voting power 3,140,972 shares Sole power to vote or direct the vote

Sole dispositive power 3,140,972 shares Sole power to dispose or direct disposition

Reporting period 03/31/2026 As-of date shown on the amendment cover

Signature date 04/29/2026 Signed by General Counsel Jay Kesslen

Key Terms

Schedule 13G/A, Units of Beneficial Interest, Beneficially owned, Sole Dispositive Power

4 terms

Schedule 13G/A regulatory

"Amendment No. 8 ) MESABI TRUST Units of Beneficial Interest"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

Units of Beneficial Interest market

"Title of class of securities: Units of Beneficial Interest"

Units of beneficial interest are pieces of ownership in a trust, fund, or pooled investment that give the holder a right to a share of the assets and income without holding the underlying property directly. Think of them as slices of a pie that entitle you to future slices of profit or distributions; investors care because these units determine how returns, risks, voting rights, and tax treatment are allocated and how easily you can buy or sell your stake.

Beneficially owned regulatory

"Amount beneficially owned: 3,140,972 Shares"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Sole Dispositive Power regulatory

"Sole power to dispose or to direct the disposition of: 3,140,972 Shares"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 8)

MESABI TRUST

(Name of Issuer)

Units of Beneficial Interest

(Title of Class of Securities)

590672101

(CUSIP Number)

03/31/2026

(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)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 590672101

1

Names of Reporting Persons

HORIZON KINETICS ASSET MANAGEMENT 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 3,140,972.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 3,140,972.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,140,972.00

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)

23.9 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: Horizon Kinetics Asset Management LLC (HKAM) is a wholly owned subsidiary of Horizon Kinetics Holding Corporation (HKHC).

SCHEDULE 13G

CUSIP Number(s): 590672101

1

Names of Reporting Persons

Horizon Kinetics Holding Corp

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 3,140,972.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 3,140,972.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,140,972.00

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)

23.9 %

12

Type of Reporting Person (See Instructions)

HC

Comment for Type of Reporting Person: HKHC is the parent company to HKAM. HKHC may be deemed to beneficially own the 3,140,972 Shares beneficially owned by HKAM.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MESABI TRUST
(b)	Address of issuer's principal executive offices: C/O DEUTSCHE BANK TRUST COMPANY AMERICAS, 1 COLUMBUS CIRCLE, 17TH FLOOR, NEW YORK, NEW YORK, 10019.
Item 2.
(a)	Name of person filing: HKAM is a wholly owned subsidiary of HKHC.
(b)	Address or principal business office or, if none, residence: 470 Park Ave S, 4th Fl S, New York, NY 10016
(c)	Citizenship: United States
(d)	Title of class of securities: Units of Beneficial Interest
(e)	CUSIP No.: 590672101
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: 3,140,972 Shares
(b)	Percent of class: 23.9%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 3,140,972 Shares
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 3,140,972 Shares
	(iv) Shared power to dispose or to direct the disposition of: 0
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.
	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.

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.

HORIZON KINETICS ASSET MANAGEMENT LLC

Signature:	/s/Jay Kesslen
Name/Title:	General Counsel
Date:	04/29/2026

Horizon Kinetics Holding Corp

Signature:	/s/Jay Kesslen
Name/Title:	General Counsel
Date:	04/29/2026

FAQ

What stake does Horizon Kinetics report in MSB on this Schedule 13G/A?

The filing reports 3,140,972 shares beneficially owned, equal to 23.9% of the class as of 03/31/2026. It states sole voting and dispositive power over all reported shares.

Does Horizon Kinetics Holding Corp also claim ownership in MSB?

Yes. The amendment states that Horizon Kinetics Holding Corp is the parent of HKAM and may be deemed to beneficially own 3,140,972 shares that HKAM holds, per the filing language.

What class of security is reported in the MSB filing?

The filing covers Units of Beneficial Interest of Mesabi Trust (CUSIP 590672101), identified as the class for which the 3,140,972 shares and 23.9% stake are reported.

What powers does the filer claim over the reported MSB shares?

The filer declares sole voting power and sole dispositive power over 3,140,972 shares, with 0 shared voting or dispositive power, according to the ownership table.

What are the key dates shown in the amendment for MSB?

The ownership is reported with an as-of date of 03/31/2026 on the cover, and the amendment is signed by General Counsel on 04/29/2026, per the signature block.