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.
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).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| BANC FUNDS CO LLC added | 530,941 | $12M | 11.1% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. trimmed | 554,723 | $11M | 10.6% | 2026-Q1 |
| Fourthstone LLC trimmed | 384,802 | $9M | 8.0% | 2026-Q1 |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 352,706 | $8M | 7.3% | 2026-Q1 |
| BlackRock, Inc. trimmed | 347,608 | $8M | 7.2% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 301,487 | $7M | 6.3% | 2026-Q1 |
| FIRST MANHATTAN CO. LLC. | 188,108 | $4M | 3.9% | 2026-Q1 |
| DIMENSIONAL FUND ADVISORS LP added | 166,633 | $4M | 3.5% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC trimmed | 147,168 | $3M | 3.1% | 2026-Q1 |
| ACADIAN ASSET MANAGEMENT LLC added | 133,976 | $3M | 2.8% | 2026-Q1 |
| UBS Group AG trimmed | 113,178 | $3M | 2.4% | 2026-Q1 |
| MARSHALL WACE, LLP added | 105,947 | $2M | 2.2% | 2026-Q1 |
| STATE STREET CORP added | 100,211 | $2M | 2.1% | 2026-Q1 |
| Cresset Asset Management, LLC trimmed | 72,000 | $2M | 1.5% | 2026-Q1 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC added | 63,776 | $1M | 1.3% | 2026-Q1 |
| AMERICAN CENTURY COMPANIES INC new | 52,544 | $1M | 1.1% | 2026-Q1 |
| Squarepoint Ops LLC added | 50,874 | $1M | 1.1% | 2026-Q1 |
| MENDON CAPITAL ADVISORS CORP | 47,312 | $1M | 1.0% | 2026-Q1 |
| NORTHERN TRUST CORP trimmed | 46,935 | $1M | 1.0% | 2026-Q1 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 39,661 | $880K | 0.8% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 38,951 | $865K | 0.8% | 2026-Q1 |
| Empowered Funds, LLC added | 34,396 | $764K | 0.7% | 2026-Q1 |
| Connor, Clark & Lunn Investment Management Ltd. added | 33,056 | $734K | 0.7% | 2026-Q1 |
| MORGAN STANLEY trimmed | 24,380 | $541K | 0.5% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 23,518 | $522K | 0.5% | 2026-Q1 |
| ELCO Management Co., LLC | 22,312 | $495K | 0.5% | 2026-Q1 |
| Creative Planning added | 22,270 | $494K | 0.5% | 2026-Q1 |
| Daytona Street Capital LLC | 18,000 | $405K | 0.4% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 17,801 | $395K | 0.4% | 2026-Q1 |
| Trexquant Investment LP added | 17,039 | $378K | 0.4% | 2026-Q1 |
| Bank of New York Mellon Corp trimmed | 16,826 | $374K | 0.4% | 2026-Q1 |
| BARCLAYS PLC trimmed | 16,513 | $367K | 0.3% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 14,400 | $320K | 0.3% | 2026-Q1 |
| HighTower Advisors, LLC added | 13,428 | $298K | 0.3% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 12,827 | $285K | 0.3% | 2026-Q1 |
| Atlantic Union Bankshares Corp | 12,600 | $280K | 0.3% | 2026-Q1 |
| XTX Topco Ltd new | 10,110 | $224K | 0.2% | 2026-Q1 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP trimmed | 9,732 | $216K | 0.2% | 2026-Q1 |
| Nuveen, LLC new | 9,161 | $203K | 0.2% | 2026-Q1 |
| CALDWELL SUTTER CAPITAL, INC. | 8,818 | $196K | 0.2% | 2026-Q1 |
| OSAIC HOLDINGS, INC. | 6,709 | $149K | 0.1% | 2026-Q1 |
| Spire Wealth Management | 6,562 | $146K | 0.1% | 2026-Q1 |
| Hughes Financial Services, LLC | 5,440 | $121K | 0.1% | 2026-Q1 |
| RHUMBLINE ADVISERS trimmed | 5,116 | $114K | 0.1% | 2026-Q1 |
| DEUTSCHE BANK AG\ | 5,026 | $112K | 0.1% | 2026-Q1 |
| NEW YORK STATE COMMON RETIREMENT FUND | 3,484 | $77K | 0.1% | 2026-Q1 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added | 3,357 | $75K | 0.1% | 2026-Q1 |
| JPMORGAN CHASE & CO trimmed | 2,875 | $63K | 0.1% | 2026-Q1 |
| BNP PARIBAS FINANCIAL MARKETS added | 2,787 | $62K | 0.1% | 2026-Q1 |
| Cassaday & Co Wealth Management LLC new | 2,730 | $61K | 0.1% | 2026-Q1 |
| WELLS FARGO & COMPANY/MN trimmed | 2,582 | $57K | 0.1% | 2026-Q1 |
| Vanguard Global Advisers, LLC new | 2,563 | $57K | 0.1% | 2026-Q1 |
| Police & Firemen's Retirement System of New Jersey | 1,763 | $39K | 0.0% | 2026-Q1 |
| Tower Research Capital LLC (TRC) added | 1,094 | $24K | 0.0% | 2026-Q1 |
| Steward Partners Investment Advisory, LLC | 1,050 | $23K | 0.0% | 2026-Q1 |
| US BANCORP \DE\ | 1,000 | $22K | 0.0% | 2026-Q1 |
| FIRST UNITED BANK & TRUST | 790 | $18K | 0.0% | 2026-Q1 |
| Russell Investments Group, Ltd. added | 777 | $17K | 0.0% | 2026-Q1 |
| Ameritas Investment Partners, Inc. | 718 | $16K | 0.0% | 2026-Q1 |
| Legal & General Group Plc | 636 | $14K | 0.0% | 2026-Q1 |
| ROYAL BANK OF CANADA trimmed | 550 | $13K | 0.0% | 2026-Q1 |
| State of Alaska, Department of Revenue | 596 | $13K | 0.0% | 2026-Q1 |
| Rockefeller Capital Management L.P. added | 556 | $12K | 0.0% | 2026-Q1 |
| TOTH FINANCIAL ADVISORY CORP added | 542 | $12K | 0.0% | 2026-Q1 |
| STRS OHIO trimmed | 500 | $11K | 0.0% | 2026-Q1 |
| FMR LLC added | 472 | $10K | 0.0% | 2026-Q1 |
| FEDERATED HERMES, INC. trimmed | 455 | $10K | 0.0% | 2026-Q1 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed | 381 | $8K | 0.0% | 2026-Q1 |
| CITIGROUP INC added | 320 | $7K | 0.0% | 2026-Q1 |
| Sterling Capital Management LLC trimmed | 223 | $5K | 0.0% | 2026-Q1 |
| CWM, LLC added | 173 | $4K | 0.0% | 2026-Q1 |
| Farther Finance Advisors, LLC | 94 | $2K | 0.0% | 2026-Q1 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC new | 88 | $2K | 0.0% | 2026-Q1 |
| SBI Securities Co., Ltd. | 83 | $2K | 0.0% | 2026-Q1 |
| GAMMA Investing LLC added | 29 | $644 | 0.0% | 2026-Q1 |
| PNC FINANCIAL SERVICES GROUP, INC. added | 26 | $577 | 0.0% | 2026-Q1 |
| Allworth Financial LP new | 15 | $333 | 0.0% | 2026-Q1 |
| MAI Capital Management added | 10 | $222 | 0.0% | 2026-Q1 |
| Root Financial Partners, LLC new | 7 | $155 | 0.0% | 2026-Q1 |
| ROTHSCHILD INVESTMENT LLC added | 5 | $111 | 0.0% | 2026-Q1 |
| Essential Partners LLC | 4 | $89 | 0.0% | 2026-Q1 |
| VANGUARD GROUP INC trimmed | 379,278 | $8M | 7.2% | 2025-Q4 stale |
| Cutler Capital Management, LLC trimmed | 86,297 | $1M | 1.4% | 2025-Q1 stale |
| MILLENNIUM MANAGEMENT LLC added | 32,052 | $668K | 0.6% | 2025-Q3 stale |
| SALZHAUER MICHAEL trimmed | 33,448 | $559K | 0.5% | 2025-Q1 stale |
| StoneX Group Inc. | 23,940 | $452K | 0.4% | 2025-Q2 stale |
| TWO SIGMA ADVISERS, LP trimmed | 17,500 | $365K | 0.3% | 2025-Q3 stale |
| JANE STREET GROUP, LLC added | 21,270 | $356K | 0.3% | 2025-Q1 stale |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed | 15,075 | $285K | 0.3% | 2025-Q2 stale |
| Forum Financial Management, LP | 13,439 | $254K | 0.2% | 2025-Q2 stale |
| GSA CAPITAL PARTNERS LLP trimmed | 11,888 | $248K | 0.2% | 2025-Q3 stale |
| Provident Wealth Management, LLC | 10,932 | $223K | 0.2% | 2025-Q4 stale |
| Sandy Spring Bank | 12,600 | $211K | 0.2% | 2025-Q1 stale |
| TWO SIGMA INVESTMENTS, LP trimmed | 10,072 | $210K | 0.2% | 2025-Q3 stale |
| Qube Research & Technologies Ltd trimmed | 11,710 | $196K | 0.2% | 2025-Q1 stale |
| BANK OF AMERICA CORP /DE/ added | 8,110 | $165K | 0.2% | 2025-Q4 stale |
| MetLife Investment Management, LLC trimmed | 4,079 | $83K | 0.1% | 2025-Q4 stale |
| Kestra Advisory Services, LLC new | 1,990 | $41K | 0.0% | 2025-Q4 stale |
| RAYMOND JAMES FINANCIAL INC new | 704 | $13K | 0.0% | 2025-Q2 stale |
| AMALGAMATED BANK trimmed | 221 | $4K | 0.0% | 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.
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.