Fourthstone discloses small passive stake in MainStreet Bancshares (MNSB) common stock

Rhea-AI Filing Summary

MainStreet Bancshares, Inc. is the issuer of Common Stock, par value $4.00 per share, held by several related investment entities managed by Fourthstone LLC. Fourthstone LLC, as a registered investment adviser, directly holds 47,432 shares of MainStreet Bancshares’ common stock on behalf of its advisory clients, representing 0.67% of the class. The stake is reported jointly by Fourthstone LLC, affiliated funds, Fourthstone GP LLC, and L. Phillip Stone IV, who may be deemed to beneficially own these securities through control relationships. All reporting persons state that the shares were acquired in the ordinary course of business and not for the purpose or effect of changing or influencing control of MainStreet Bancshares. The reported percentages are based on 7,117,438 shares outstanding as of April 30, 2026, as referenced from the issuer’s Form 10-Q.

Key Figures

Fourthstone LLC shares owned: 47,432 shares Fourthstone LLC percent of class: 0.67% Shares outstanding: 7,117,438 shares +3 more

6 metrics

Fourthstone LLC shares owned 47,432 shares Common Stock of MainStreet Bancshares held on behalf of advisory clients

Fourthstone LLC percent of class 0.67% Percentage of MainStreet Bancshares common stock class reported as beneficially owned

Shares outstanding 7,117,438 shares MainStreet Bancshares common stock outstanding as of April 30, 2026

Fourthstone Master Opportunity Fund stake 31,739 shares (0.45%) Beneficial ownership of MainStreet Bancshares common stock

Fourthstone QP Opportunity Fund stake 10,590 shares (0.15%) Beneficial ownership of MainStreet Bancshares common stock

Fourthstone Small-Cap Financials Fund stake 5,103 shares (0.07%) Beneficial ownership of MainStreet Bancshares common stock

Key Terms

beneficially own, dispositive power, investment adviser, Schedule 13G, +1 more

5 terms

beneficially own financial

"The percentages reported in Row 11 of each cover page are based on 7,117,438 shares of Common Stock..."

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

dispositive power financial

"Sole Dispositive Power 0.00 8 | Shared Dispositive Power 47,432.00"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

investment adviser financial

"Fourthstone LLC acquired the Issuer's shares in the ordinary course of business as a registered investment adviser"

An investment adviser is a person or firm that professionally manages money and gives recommendations about buying, selling, or holding investments. Like a financial coach or guide, they have a legal duty to act in a client's best financial interest, so their advice, fees and potential conflicts can directly affect returns and risk — making their role important for investors who want informed, accountable help with portfolios.

Schedule 13G regulatory

"Ownership of 5 Percent or Less of a Class."

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

percent of class financial

"Percent of class: 0.67 %"

Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.

FAQ

What ownership stake in MNSB does Fourthstone LLC report in this Schedule 13G/A?

Fourthstone LLC reports beneficial ownership of 47,432 shares of MainStreet Bancshares (MNSB) common stock, representing 0.67% of the class, held on behalf of its advisory clients in the ordinary course of business.

Is Fourthstone’s MNSB ownership reported as a passive investment?

Yes. The reporting persons certify the MNSB securities were not acquired and are not held for the purpose or effect of changing or influencing control of MainStreet Bancshares, and not in connection with any transaction having that effect.

What share count did MainStreet Bancshares (MNSB) have outstanding for this 13G/A calculation?

The reported ownership percentages are based on 7,117,438 shares of MainStreet Bancshares common stock outstanding as of April 30, 2026, as referenced from the company’s Form 10-Q filed on May 8, 2026.

Who are the reporting persons in this MainStreet Bancshares (MNSB) Schedule 13G/A?

The reporting persons are Fourthstone LLC, Fourthstone Master Opportunity Fund Ltd., Fourthstone GP LLC, Fourthstone QP Opportunity Fund LP, Fourthstone Small-Cap Financials Fund LP, and L. Phillip Stone IV, Managing Member of Fourthstone LLC and Fourthstone GP.

How much voting and dispositive power over MNSB shares does Fourthstone LLC report?

Fourthstone LLC reports 0 shares with sole voting or dispositive power and 47,432 shares with shared voting and shared dispositive power, reflecting its advisory role over client accounts holding MainStreet Bancshares common stock.

Does this Schedule 13G/A show Fourthstone owning more than 5% of MNSB?

No. The filing explicitly states ownership of 5 percent or less of the MNSB common stock class. The largest reported percentage, for Fourthstone LLC and L. Phillip Stone IV, is 0.67% of outstanding shares.

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Available on EDGAR 08/14/2026 - 04:53 PM Accepted by SEC EDGAR 08/14/2026 - 04:53 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

MainStreet Bancshares, Inc.

(Name of Issuer)

Common Stock, par value $4.00 per share

(Title of Class of Securities)

56064Y100

(CUSIP Number)

06/30/2026

(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): 56064Y100

1

Names of Reporting Persons

Fourthstone 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 47,432.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 47,432.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

47,432.00

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)

0.67 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: See Item 4 for a description of the information reported in rows (6), (8), (9) and (11).

SCHEDULE 13G

CUSIP Number(s): 56064Y100

1

Names of Reporting Persons

Fourthstone Master Opportunity Fund Ltd

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

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 31,739.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 31,739.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

31,739.00

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)

0.45 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: See Item 4 for a description of the information reported in rows (6), (8), (9) and (11).

SCHEDULE 13G

CUSIP Number(s): 56064Y100

1

Names of Reporting Persons

Fourthstone 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 15,693.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 15,693.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

15,693.00

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)

0.22 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: See Item 4 for a description of the information reported in rows (6), (8), (9) and (11).

SCHEDULE 13G

CUSIP Number(s): 56064Y100

1

Names of Reporting Persons

Fourthstone QP Opportunity Fund 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 10,590.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 10,590.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

10,590.00

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)

0.15 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: See Item 4 for a description of the information reported in rows (6), (8), (9) and (11).

SCHEDULE 13G

CUSIP Number(s): 56064Y100

1

Names of Reporting Persons

Fourthstone Small-Cap Financials Fund 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 5,103.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,103.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,103.00

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)

0.07 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: See Item 4 for a description of the information reported in rows (6), (8), (9) and (11).

SCHEDULE 13G

CUSIP Number(s): 56064Y100

1

Names of Reporting Persons

L. Phillip Stone, IV

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 47,432.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 47,432.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

47,432.00

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)

0.67 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: See Item 4 for a description of the information reported in rows (6), (8), (9) and (11).

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MainStreet Bancshares, Inc.
(b)	Address of issuer's principal executive offices: 10089 FAIRFAX BOULEVARD, FAIRFAX, VA, 22030
Item 2.
(a)	Name of person filing: This Schedule 13G is being filed by Fourthstone LLC, a Delaware Limited Liability Company and Investment Adviser ("Fourthstone"). The persons reporting information on this Schedule 13G include, in addition to Fourthstone, a company incorporated in the Cayman Islands ("Fourthstone Master Opportunity Fund"), a Delaware Limited Partnership ("Fourthstone QP Opportunity"), a Delaware Limited Partnership ("Fourthstone Small-Cap Financials"), a Delaware Limited Liability Company ("Fourthstone GP, " General Partner of Fourthstone QP Opportunity and Fourthstone Small-Cap Financials), and L. Phillip Stone, IV, a citizen of the United States of America, who is the Managing Member of Fourthstone and Fourthstone GP (each, a "Reporting Person" and, together, the "Reporting Persons"). Fourthstone directly holds 47,432 shares of Common Stock on behalf of its advisory clients. Each of the Reporting Persons listed in this filing certify 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 effect.
(b)	Address or principal business office or, if none, residence: The principal business address of each of the Reporting Persons is as follows: The registered office of Fourthstone LLC, Fourthstone Master Opportunity Fund Ltd., Fourthstone GP LLC, Fourthstone QP Opportunity Fund LP, Fourthstone Small-Cap Financials Fund LP is 575 Maryville Centre Drive, Suite 110, St. Louis, MO 63141.
(c)	Citizenship: See response to Item 4 of each of the cover pages.
(d)	Title of class of securities: Common Stock, par value $4.00 per share
(e)	CUSIP No.: 56064Y100
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: Fourthstone LLC acquired the Issuer's shares in the ordinary course of business as a registered investment adviser and not with the purpose nor with the effect of influencing the control of the Issuer. Fourthstone GP LLC is the general partner of and may be deemed to beneficially own securities owned by Fourthstone QP Opportunity Fund LP and Fourthstone Small-Cap Financials Fund LP. L. Phillip Stone, IV, is the Managing Member of Fourthstone LLC and Fourthstone GP and may be deemed to beneficially own securities owned by Fourthstone. The percentages reported in Row 11 of each cover page are based on 7,117,438 shares of Common Stock (as defined below) of the Issuer (as defined below) outstanding as of April 30, 2026, based on the Issuer's Form 10-Q filed on May 8, 2026.
(b)	Percent of class: 0.67 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See responses to Item 5 on each cover page.
	(ii) Shared power to vote or to direct the vote: See responses to Item 6 on each cover page.
	(iii) Sole power to dispose or to direct the disposition of: See responses to Item 7 on each cover page.
	(iv) Shared power to dispose or to direct the disposition of: See responses to Item 8 on each cover page.
Item 5.	Ownership of 5 Percent or Less of a Class.
	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.

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.

Fourthstone LLC

Signature:	Amy M. Stone
Name/Title:	Chief Executive Officer
Date:	08/14/2026

Fourthstone Master Opportunity Fund Ltd

Signature:	Amy M. Stone
Name/Title:	Chief Executive Officer
Date:	08/14/2026

Fourthstone GP LLC

Signature:	L. Phillip Stone, IV
Name/Title:	Managing Member of Fourthstone GP LLC
Date:	08/14/2026

Fourthstone QP Opportunity Fund LP

Signature:	Amy M. Stone
Name/Title:	Chief Executive Officer
Date:	08/14/2026

Fourthstone Small-Cap Financials Fund LP

Signature:	Amy M. Stone
Name/Title:	Chief Executive Officer
Date:	08/14/2026

L. Phillip Stone, IV

Signature:	L. Phillip Stone, IV
Name/Title:	Self, Principal owner of Fourthstone LLC
Date:	08/14/2026