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Institutional Ownership · SEC Form 13F

Who owns MainStreet Bancshares, Inc. (MNSB)


Which tracked institutional funds hold MNSB, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MNSB company fundamentals →

Ownership as of the 2026-Q1 13F filings. 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.

83
Institutional holders
4M
Shares held (tracked funds)
56.5%
Of shares outstanding

How the tape is positioned

13 tracked funds added or opened MNSB while 6 trimmed or exited it between 2025-Q4 and 2026-Q1 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.

A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.

Conviction spread

MNSB’s largest tracked holder by dollar value, BANC FUNDS CO LLC, sizes it at 2.2% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 2.2pp conviction gap — its largest holder concentrates the name more heavily than the typical one.

Book-share is each fund’s reported value in MNSB divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.

Institutional & insider positioning

Between 2025-Q4 and 2026-Q1, across 83 tracked filers holding MNSB, 39 increased or opened the position and 29 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.

This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.

New buyers & exits

Funds opening or closing a position in MNSB between the 2025-Q4 and 2026-Q1 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.

New buyers 4

  • VANGUARD CAPITAL MANAGEMENT LLC$7M
  • AMERICAN CENTURY COMPANIES INC$1M
  • VANGUARD PORTFOLIO MANAGEMENT LLC$880K
  • VANGUARD FIDUCIARY TRUST CO$865K

Full exits 1

  • VANGUARD GROUP INC$8M

Largest adds

  • BANC FUNDS CO LLC$3M
  • MARSHALL WACE, LLP$1M
  • ACADIAN ASSET MANAGEMENT LLC$999K
  • DIMENSIONAL FUND ADVISORS LP$882K
  • STATE STREET CORP$727K
  • BlackRock, Inc.$584K

Largest trims

  • Fourthstone LLC$7M
  • Cresset Asset Management, LLC$5M
  • ALLIANCEBERNSTEIN L.P.$3M
  • RENAISSANCE TECHNOLOGIES LLC$678K
  • CITADEL ADVISORS LLC$278K

Institutional holders

One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).

FundSharesReported value% of valueQuarter
BANC FUNDS CO LLC added530,941$12M11.1%2026-Q1
ALLIANCEBERNSTEIN L.P. trimmed554,723$11M10.6%2026-Q1
Fourthstone LLC trimmed384,802$9M8.0%2026-Q1
WELLINGTON MANAGEMENT GROUP LLP trimmed352,706$8M7.3%2026-Q1
BlackRock, Inc. trimmed347,608$8M7.2%2026-Q1
VANGUARD CAPITAL MANAGEMENT LLC new301,487$7M6.3%2026-Q1
FIRST MANHATTAN CO. LLC.188,108$4M3.9%2026-Q1
DIMENSIONAL FUND ADVISORS LP added166,633$4M3.5%2026-Q1
GEODE CAPITAL MANAGEMENT, LLC trimmed147,168$3M3.1%2026-Q1
ACADIAN ASSET MANAGEMENT LLC added133,976$3M2.8%2026-Q1
UBS Group AG trimmed113,178$3M2.4%2026-Q1
MARSHALL WACE, LLP added105,947$2M2.2%2026-Q1
STATE STREET CORP added100,211$2M2.1%2026-Q1
Cresset Asset Management, LLC trimmed72,000$2M1.5%2026-Q1
BRIDGEWAY CAPITAL MANAGEMENT, LLC added63,776$1M1.3%2026-Q1
AMERICAN CENTURY COMPANIES INC new52,544$1M1.1%2026-Q1
Squarepoint Ops LLC added50,874$1M1.1%2026-Q1
MENDON CAPITAL ADVISORS CORP47,312$1M1.0%2026-Q1
NORTHERN TRUST CORP trimmed46,935$1M1.0%2026-Q1
VANGUARD PORTFOLIO MANAGEMENT LLC new39,661$880K0.8%2026-Q1
VANGUARD FIDUCIARY TRUST CO new38,951$865K0.8%2026-Q1
Empowered Funds, LLC added34,396$764K0.7%2026-Q1
Connor, Clark & Lunn Investment Management Ltd. added33,056$734K0.7%2026-Q1
MORGAN STANLEY trimmed24,380$541K0.5%2026-Q1
CITADEL ADVISORS LLC trimmed23,518$522K0.5%2026-Q1
ELCO Management Co., LLC22,312$495K0.5%2026-Q1
Creative Planning added22,270$494K0.5%2026-Q1
Daytona Street Capital LLC18,000$405K0.4%2026-Q1
CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed17,801$395K0.4%2026-Q1
Trexquant Investment LP added17,039$378K0.4%2026-Q1
Bank of New York Mellon Corp trimmed16,826$374K0.4%2026-Q1
BARCLAYS PLC trimmed16,513$367K0.3%2026-Q1
RENAISSANCE TECHNOLOGIES LLC trimmed14,400$320K0.3%2026-Q1
HighTower Advisors, LLC added13,428$298K0.3%2026-Q1
GOLDMAN SACHS GROUP INC added12,827$285K0.3%2026-Q1
Atlantic Union Bankshares Corp12,600$280K0.3%2026-Q1
XTX Topco Ltd new10,110$224K0.2%2026-Q1
ARROWSTREET CAPITAL, LIMITED PARTNERSHIP trimmed9,732$216K0.2%2026-Q1
Nuveen, LLC new9,161$203K0.2%2026-Q1
CALDWELL SUTTER CAPITAL, INC.8,818$196K0.2%2026-Q1
OSAIC HOLDINGS, INC.6,709$149K0.1%2026-Q1
Spire Wealth Management6,562$146K0.1%2026-Q1
Hughes Financial Services, LLC5,440$121K0.1%2026-Q1
RHUMBLINE ADVISERS trimmed5,116$114K0.1%2026-Q1
DEUTSCHE BANK AG\5,026$112K0.1%2026-Q1
NEW YORK STATE COMMON RETIREMENT FUND3,484$77K0.1%2026-Q1
MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added3,357$75K0.1%2026-Q1
JPMORGAN CHASE & CO trimmed2,875$63K0.1%2026-Q1
BNP PARIBAS FINANCIAL MARKETS added2,787$62K0.1%2026-Q1
Cassaday & Co Wealth Management LLC new2,730$61K0.1%2026-Q1
WELLS FARGO & COMPANY/MN trimmed2,582$57K0.1%2026-Q1
Vanguard Global Advisers, LLC new2,563$57K0.1%2026-Q1
Police & Firemen's Retirement System of New Jersey1,763$39K0.0%2026-Q1
Tower Research Capital LLC (TRC) added1,094$24K0.0%2026-Q1
Steward Partners Investment Advisory, LLC1,050$23K0.0%2026-Q1
US BANCORP \DE\1,000$22K0.0%2026-Q1
FIRST UNITED BANK & TRUST790$18K0.0%2026-Q1
Russell Investments Group, Ltd. added777$17K0.0%2026-Q1
Ameritas Investment Partners, Inc.718$16K0.0%2026-Q1
Legal & General Group Plc636$14K0.0%2026-Q1
ROYAL BANK OF CANADA trimmed550$13K0.0%2026-Q1
State of Alaska, Department of Revenue596$13K0.0%2026-Q1
Rockefeller Capital Management L.P. added556$12K0.0%2026-Q1
TOTH FINANCIAL ADVISORY CORP added542$12K0.0%2026-Q1
STRS OHIO trimmed500$11K0.0%2026-Q1
FMR LLC added472$10K0.0%2026-Q1
FEDERATED HERMES, INC. trimmed455$10K0.0%2026-Q1
CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed381$8K0.0%2026-Q1
CITIGROUP INC added320$7K0.0%2026-Q1
Sterling Capital Management LLC trimmed223$5K0.0%2026-Q1
CWM, LLC added173$4K0.0%2026-Q1
Farther Finance Advisors, LLC94$2K0.0%2026-Q1
UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC new88$2K0.0%2026-Q1
SBI Securities Co., Ltd.83$2K0.0%2026-Q1
GAMMA Investing LLC added29$6440.0%2026-Q1
PNC FINANCIAL SERVICES GROUP, INC. added26$5770.0%2026-Q1
Allworth Financial LP new15$3330.0%2026-Q1
MAI Capital Management added10$2220.0%2026-Q1
Root Financial Partners, LLC new7$1550.0%2026-Q1
ROTHSCHILD INVESTMENT LLC added5$1110.0%2026-Q1
Essential Partners LLC4$890.0%2026-Q1
VANGUARD GROUP INC trimmed379,278$8M7.2%2025-Q4 stale
Cutler Capital Management, LLC trimmed86,297$1M1.4%2025-Q1 stale
MILLENNIUM MANAGEMENT LLC added32,052$668K0.6%2025-Q3 stale
SALZHAUER MICHAEL trimmed33,448$559K0.5%2025-Q1 stale
StoneX Group Inc.23,940$452K0.4%2025-Q2 stale
TWO SIGMA ADVISERS, LP trimmed17,500$365K0.3%2025-Q3 stale
JANE STREET GROUP, LLC added21,270$356K0.3%2025-Q1 stale
SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed15,075$285K0.3%2025-Q2 stale
Forum Financial Management, LP13,439$254K0.2%2025-Q2 stale
GSA CAPITAL PARTNERS LLP trimmed11,888$248K0.2%2025-Q3 stale
Provident Wealth Management, LLC10,932$223K0.2%2025-Q4 stale
Sandy Spring Bank12,600$211K0.2%2025-Q1 stale
TWO SIGMA INVESTMENTS, LP trimmed10,072$210K0.2%2025-Q3 stale
Qube Research & Technologies Ltd trimmed11,710$196K0.2%2025-Q1 stale
BANK OF AMERICA CORP /DE/ added8,110$165K0.2%2025-Q4 stale
MetLife Investment Management, LLC trimmed4,079$83K0.1%2025-Q4 stale
Kestra Advisory Services, LLC new1,990$41K0.0%2025-Q4 stale
RAYMOND JAMES FINANCIAL INC new704$13K0.0%2025-Q2 stale
AMALGAMATED BANK trimmed221$4K0.0%2025-Q4 stale

Ownership over time

Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.

HoldersTotal shares

Reading this table

Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.

About 13F filings

A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.

Learn how to read institutional ownership