Mark Campbell Winmill - 03 Dec 2025 SCHEDULE 13D/A Report for GLOBAL SELF STORAGE, INC. Common Stock, $0.01 par value per share (SELF)

Filing manager: Mark Campbell Winmill
Reporting owner: Mark Campbell Winmill
Security: GLOBAL SELF STORAGE, INC. Common Stock, $0.01 par value per share
Beneficially owned shares: 947,735 shares
Large-stake signal: Form
SCHEDULE 13D/A
Active or control-oriented beneficial ownership filing.
Ownership
8.4%
Beneficial ownership of this reported class.
Shares
947,735 shares
Shares beneficially owned as disclosed.
Event date
03 Dec 2025
Date tied to the ownership event or amendment.
Accepted by SEC
05 Dec 2025
EDGAR acceptance date.
How to read this large-stake filing
Schedule 13D/G filings focus on beneficial ownership stakes, not a full portfolio.
Compare this filing with the holder history and issuer page before treating the percentage as a current position.
Use amendments to understand whether the disclosed stake increased, decreased, or changed reporting status.
Class ownership: 8.4%
Symbol: SELF
Shares outstanding: 11,282,563 shares
SEC form: SCHEDULE 13D/A
Accepted by SEC: 05 Dec 2025, 16:26:25 UTC
Event date: 03 Dec 2025
Prior SEC filing: 21 May 2025
Source filing: View source filing

Key filing fact

Mark Campbell Winmill disclosed 8.4% ownership in GLOBAL SELF STORAGE, INC. Common Stock, $0.01 par value per share (SELF) on 03 Dec 2025.

Key facts

Mark Campbell Winmill filed SCHEDULE 13D/A for GLOBAL SELF STORAGE, INC. Common Stock, $0.01 par value per share (SELF).
Disclosed ownership: 8.4%.
Date of event: 03 Dec 2025.

This page turns one Schedule 13D/G filing into a quick large-stake read before the raw reporting-person rows.
Use the linked SEC filing as the source of truth for ownership percentages, shares, and reporting-party details.

Backed by Schedule 13D/13G

Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.

Reporting persons

Names, ownership percentages, voting power, signatures, titles, and CIKs as disclosed in this Schedule 13D/G filing.

Name	Ownership	Shares owned	Sole voting power	Shared voting power	Signature	Title	CIK
Mark Campbell Winmill	8.4%	947,735	339,238	608,497	/s/ Mark C. Winmill	Mark Campbell Winmill	0001019264
Thomas Bassett Winmill	5.2%	587,600	1,100	586,500	/s/ Thomas B. Winmill	Thomas Bassett Winmill	0001018500
Winmill Family Trust	5.2%	586,500	0	586,500	/s/ Thomas B. Winmill	Thomas B. Winmill/Trustee
Winmill & Co. Incorporated	5.2%	586,500	147,641	438,859	/s/ Donald Klimoski II	Donald Klimoski II/Co-General Counsel	0000052234
Midas Securities Group, Inc.	3.9%	438,859	135,101	303,758	/s/ Russell Kamerman	Russell Kamerman/General Counsel	0001141394
TUXIS CORP	2.7%	303,758	303,758	0	/s/ Donald Klimoski II	Donald Klimoski II/General Counsel	0000736952

CIK / CUSIP context first

Broader feeds