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Institutional Ownership · SEC Form 13F

Who owns NB Bancorp, Inc. Common Stock (NBBK)


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

Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.

156
Institutional holders
22M
Shares held (tracked funds)
47.9%
Of shares outstanding

How the tape is positioned

31 tracked funds added or opened NBBK while 28 trimmed or exited it between 2026-Q1 and 2026-Q2 — 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

NBBK’s largest tracked holder by dollar value, BlackRock, Inc., sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp gap the other way — the median holder sizes NBBK more heavily than its largest holder by dollar value does.

Book-share is each fund’s reported value in NBBK 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 2026-Q1 and 2026-Q2, across 156 tracked filers holding NBBK, 79 increased or opened the position and 81 reduced or closed it; over the same quarter, open-market insider Form 4s were net purchases.

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 NBBK between the 2026-Q1 and 2026-Q2 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 3

  • MARSHALL WACE, LLP$3M
  • Y-Intercept (Hong Kong) Ltd$1M
  • Trexquant Investment LP$979K

Full exits 12

  • WELLINGTON MANAGEMENT GROUP LLP$15M
  • Tieton Capital Management, LLC$12M
  • OP Asset Management Ltd$1M
  • JANE STREET GROUP, LLC$1M
  • LAZARD ASSET MANAGEMENT LLC$1M
  • SUSQUEHANNA INTERNATIONAL GROUP, LLP$1M

Largest adds

  • AltraVue Capital, LLC$7M
  • BlackRock, Inc.$5M
  • DIMENSIONAL FUND ADVISORS LP$5M
  • STATE STREET CORP$4M
  • CITADEL ADVISORS LLC$4M
  • Legato Capital Management LLC$2M

Largest trims

  • Pertento Partners LLP$15M
  • SEI INVESTMENTS CO$3M
  • RENAISSANCE TECHNOLOGIES LLC$3M
  • GOLDMAN SACHS GROUP INC$2M
  • TWO SIGMA INVESTMENTS, LP$2M
  • MILLENNIUM MANAGEMENT LLC$2M

Institutional holders

One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.

FundSharesReported value% of valueQuarter
BlackRock, Inc. added3,331,544$70M15.4%2026-Q2
VANGUARD CAPITAL MANAGEMENT LLC trimmed1,670,835$35M7.7%2026-Q2
AltraVue Capital, LLC added1,655,108$35M7.6%2026-Q2
Pertento Partners LLP trimmed1,475,770$31M6.8%2026-Q2
STATE STREET CORP added1,471,766$31M6.8%2026-Q2
GEODE CAPITAL MANAGEMENT, LLC added1,153,217$24M5.3%2026-Q2
DIMENSIONAL FUND ADVISORS LP added753,320$16M3.5%2026-Q2
GOLDMAN SACHS GROUP INC trimmed571,954$12M2.6%2026-Q2
HOTCHKIS & WILEY CAPITAL MANAGEMENT LLC added501,172$11M2.3%2026-Q2
Nuveen, LLC added498,869$11M2.3%2026-Q2
FMR LLC added497,305$11M2.3%2026-Q2
VANGUARD PORTFOLIO MANAGEMENT LLC added397,046$8M1.8%2026-Q2
Legato Capital Management LLC added366,090$8M1.7%2026-Q2
NORTHERN TRUST CORP added360,492$8M1.7%2026-Q2
NEW YORK STATE COMMON RETIREMENT FUND added346,155$7M1.6%2026-Q2
CHARLES SCHWAB INVESTMENT MANAGEMENT INC added318,612$7M1.5%2026-Q2
CITADEL ADVISORS LLC added289,814$6M1.3%2026-Q2
TWO SIGMA INVESTMENTS, LP trimmed277,027$6M1.3%2026-Q2
AMERICAN CENTURY COMPANIES INC trimmed261,866$6M1.2%2026-Q2
VANGUARD FIDUCIARY TRUST CO trimmed253,951$5M1.2%2026-Q2
MORGAN STANLEY trimmed229,194$5M1.1%2026-Q2
BRIDGEWAY CAPITAL MANAGEMENT, LLC added221,399$5M1.0%2026-Q2
Empowered Funds, LLC added181,399$4M0.8%2026-Q2
HENNESSY ADVISORS INC trimmed178,000$4M0.8%2026-Q2
Bank of New York Mellon Corp added171,541$4M0.8%2026-Q2
D. E. Shaw & Co., Inc. added149,931$3M0.7%2026-Q2
SEI INVESTMENTS CO trimmed142,346$3M0.7%2026-Q2
FIRST TRUST ADVISORS LP added142,253$3M0.7%2026-Q2
UBS Group AG added140,405$3M0.6%2026-Q2
RENAISSANCE TECHNOLOGIES LLC trimmed131,440$3M0.6%2026-Q2
INTERNATIONAL ASSETS INVESTMENT MANAGEMENT, LLC131,013$3M0.6%2026-Q2
ALLIANCEBERNSTEIN L.P.130,219$3M0.6%2026-Q2
PANAGORA ASSET MANAGEMENT INC trimmed129,355$3M0.6%2026-Q2
Qube Research & Technologies Ltd trimmed127,236$3M0.6%2026-Q2
Financial Engines Advisors L.L.C. added126,788$3M0.6%2026-Q2
MARSHALL WACE, LLP trimmed123,112$3M0.6%2026-Q2
AQR CAPITAL MANAGEMENT LLC trimmed116,349$2M0.5%2026-Q2
MANGROVE PARTNERS IM, LLC111,356$2M0.5%2026-Q2
Invesco Ltd. trimmed97,941$2M0.5%2026-Q2
Oppenheimer & Close, LLC82,999$2M0.4%2026-Q2
MILLENNIUM MANAGEMENT LLC trimmed81,447$2M0.4%2026-Q2
Integrated Wealth Concepts LLC added78,691$2M0.4%2026-Q2
Swiss National Bank77,100$2M0.4%2026-Q2
CREDIT AGRICOLE S A70,000$1M0.3%2026-Q2
MACKENZIE FINANCIAL CORP added67,441$1M0.3%2026-Q2
Creative Planning trimmed67,320$1M0.3%2026-Q2
Round Rock Advisors LLC added66,530$1M0.3%2026-Q2
Focus Partners Wealth trimmed65,728$1M0.3%2026-Q2
BNP PARIBAS FINANCIAL MARKETS added62,478$1M0.3%2026-Q2
PRINCIPAL FINANCIAL GROUP INC added59,231$1M0.3%2026-Q2
Legal & General Group Plc added56,718$1M0.3%2026-Q2
Y-Intercept (Hong Kong) Ltd added54,541$1M0.3%2026-Q2
RHUMBLINE ADVISERS trimmed52,690$1M0.2%2026-Q2
LYNCH & ASSOCIATES/IN trimmed50,334$1M0.2%2026-Q2
STILWELL VALUE LLC trimmed50,000$1M0.2%2026-Q2
BANK OF AMERICA CORP /DE/ trimmed48,905$1M0.2%2026-Q2
NIXON PEABODY TRUST CO48,516$1M0.2%2026-Q2
AMERIPRISE FINANCIAL INC added46,899$991K0.2%2026-Q2
CITIGROUP INC added46,580$984K0.2%2026-Q2
Trexquant Investment LP trimmed46,312$979K0.2%2026-Q2
PRICE T ROWE ASSOCIATES INC /MD/ added46,016$973K0.2%2026-Q2
FEDERATED HERMES, INC. added44,967$950K0.2%2026-Q2
Quantinno Capital Management LP added44,137$933K0.2%2026-Q2
WEDGE CAPITAL MANAGEMENT L L P/NC added43,216$913K0.2%2026-Q2
Mariner, LLC trimmed42,471$897K0.2%2026-Q2
XTX Topco Ltd added41,912$886K0.2%2026-Q2
DEUTSCHE BANK AG\ added41,024$867K0.2%2026-Q2
EJF Capital LP trimmed40,751$861K0.2%2026-Q2
CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM added39,017$824K0.2%2026-Q2
UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC trimmed38,359$811K0.2%2026-Q2
Aviance Capital Partners, LLC added38,173$807K0.2%2026-Q2
STATE OF WISCONSIN INVESTMENT BOARD added38,169$807K0.2%2026-Q2
ARROWSTREET CAPITAL, LIMITED PARTNERSHIP trimmed35,981$760K0.2%2026-Q2
WELLS FARGO & COMPANY/MN added35,185$743K0.2%2026-Q2
Bleakley Financial Group, LLC added34,272$724K0.2%2026-Q2
RAFFLES ASSOCIATES LP added31,874$673K0.1%2026-Q2
Allspring Global Investments Holdings, LLC added30,429$658K0.1%2026-Q2
RAYMOND JAMES FINANCIAL INC added29,914$632K0.1%2026-Q2
FRANKLIN RESOURCES INC added28,370$599K0.1%2026-Q2
LPL Financial LLC added26,409$558K0.1%2026-Q2
Rafferty Asset Management, LLC trimmed25,529$539K0.1%2026-Q2
NORTHEAST INVESTMENT MANAGEMENT25,000$528K0.1%2026-Q2
Vanguard Global Advisers, LLC added24,444$517K0.1%2026-Q2
MetLife Investment Management, LLC added24,072$509K0.1%2026-Q2
BARCLAYS PLC added23,951$506K0.1%2026-Q2
VANGUARD ASSET MANAGEMENT, Ltd23,484$496K0.1%2026-Q2
Russell Investments Group, Ltd. added21,332$451K0.1%2026-Q2
MIRABELLA FINANCIAL SERVICES LLP new20,227$427K0.1%2026-Q2
Investment Advisory Group, LLC20,000$423K0.1%2026-Q2
&PARTNERS19,730$417K0.1%2026-Q2
COMMONWEALTH EQUITY SERVICES, LLC trimmed19,285$407K0.1%2026-Q2
JPMORGAN CHASE & CO trimmed19,283$409K0.1%2026-Q2
MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added18,740$396K0.1%2026-Q2
Harbor Advisors LLC added17,500$370K0.1%2026-Q2
MERCER GLOBAL ADVISORS INC /ADV added16,992$359K0.1%2026-Q2
Zurcher Kantonalbank (Zurich Cantonalbank)16,976$359K0.1%2026-Q2
KESTRA PRIVATE WEALTH SERVICES, LLC trimmed16,766$354K0.1%2026-Q2
ROCKLAND TRUST CO15,969$337K0.1%2026-Q2
Cerity Partners LLC trimmed15,558$329K0.1%2026-Q2
ExodusPoint Capital Management, LP added15,487$327K0.1%2026-Q2

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