Who owns PubMatic (PUBM)
Which tracked institutional funds hold PUBM, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See PUBM company fundamentals →
Ownership as of the 2026-Q1 13F filings (latest filed 2026-05-18). 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
26 tracked funds added or opened PUBM while 30 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
PUBM’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 PUBM more heavily than its largest holder by dollar value does.
Book-share is each fund’s reported value in PUBM 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 154 tracked filers holding PUBM, 92 increased or opened the position and 75 reduced or closed it; over the same quarter, open-market insider Form 4 buying and selling roughly offset.
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 PUBM 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 8
- VANGUARD CAPITAL MANAGEMENT LLC$13M
- Whitefort Capital Management, LP$6M
- VANGUARD PORTFOLIO MANAGEMENT LLC$5M
- VANGUARD FIDUCIARY TRUST CO$2M
- ARROWSTREET CAPITAL, LIMITED PARTNERSHIP$2M
- BRIDGEWAY CAPITAL MANAGEMENT, LLC$1M
Full exits 9
- VANGUARD GROUP INC$21M
- WELLINGTON MANAGEMENT GROUP LLP$10M
- ALGERT GLOBAL LLC$3M
- TWO SIGMA ADVISERS, LP$2M
- Walleye Capital LLC$1M
- MARSHALL WACE, LLP$1M
Largest adds
- ACADIAN ASSET MANAGEMENT LLC$5M
- CenterBook Partners LP$4M
- S SQUARED TECHNOLOGY, LLC$3M
- Graham Holdings Co$3M
- TUDOR INVESTMENT CORP ET AL$2M
- RENAISSANCE TECHNOLOGIES LLC$2M
Largest trims
- MILLENNIUM MANAGEMENT LLC$7M
- BlackRock, Inc.$3M
- NORTHWESTERN MUTUAL WEALTH MANAGEMENT CO$2M
- ROYAL BANK OF CANADA$2M
- Point72 Asset Management, L.P.$1M
- D. E. Shaw & Co., Inc.$1M
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 |
|---|---|---|---|---|
| BlackRock, Inc. added | 3,279,530 | $43M | 12.8% | 2026-Q2 |
| Graham Holdings Co added | 3,398,904 | $28M | 8.2% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 1,421,049 | $19M | 5.5% | 2026-Q2 |
| CenterBook Partners LP added | 1,742,100 | $14M | 4.2% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 1,613,769 | $13M | 3.9% | 2026-Q1 |
| ACADIAN ASSET MANAGEMENT LLC added | 1,576,540 | $13M | 3.8% | 2026-Q1 |
| STATE STREET CORP added | 854,147 | $11M | 3.3% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP trimmed | 1,245,359 | $10M | 3.0% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP added | 638,102 | $8M | 2.5% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 950,605 | $8M | 2.3% | 2026-Q1 |
| JACOBS LEVY EQUITY MANAGEMENT, INC added | 932,213 | $8M | 2.3% | 2026-Q1 |
| ROYAL BANK OF CANADA trimmed | 740,281 | $6M | 1.8% | 2026-Q1 |
| Whitefort Capital Management, LP new | 690,000 | $6M | 1.7% | 2026-Q1 |
| S SQUARED TECHNOLOGY, LLC added | 676,399 | $6M | 1.6% | 2026-Q1 |
| CITADEL ADVISORS LLC added | 414,880 | $5M | 1.6% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 638,785 | $5M | 1.5% | 2026-Q1 |
| Simcoe Capital LLC added | 486,252 | $4M | 1.2% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC added | 286,438 | $4M | 1.1% | 2026-Q2 |
| Trexquant Investment LP added | 422,423 | $3M | 1.0% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 354,200 | $3M | 0.9% | 2026-Q1 |
| TUDOR INVESTMENT CORP ET AL added | 351,112 | $3M | 0.9% | 2026-Q1 |
| MORGAN STANLEY added | 341,670 | $3M | 0.8% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 294,803 | $2M | 0.7% | 2026-Q1 |
| NORTHERN TRUST CORP added | 290,561 | $2M | 0.7% | 2026-Q1 |
| PANAGORA ASSET MANAGEMENT INC added | 276,256 | $2M | 0.7% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 238,984 | $2M | 0.6% | 2026-Q1 |
| JPMORGAN CHASE & CO added | 240,467 | $2M | 0.6% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 230,629 | $2M | 0.6% | 2026-Q1 |
| JANE STREET GROUP, LLC added | 210,000 | $2M | 0.5% | 2026-Q1 |
| Quantinno Capital Management LP added | 206,815 | $2M | 0.5% | 2026-Q1 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP new | 206,287 | $2M | 0.5% | 2026-Q1 |
| P.A.W. CAPITAL CORP added | 180,000 | $1M | 0.4% | 2026-Q1 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC new | 175,300 | $1M | 0.4% | 2026-Q1 |
| Invesco Ltd. trimmed | 103,232 | $1M | 0.4% | 2026-Q2 |
| Pinnacle Holdings, LLC added | 157,884 | $1M | 0.4% | 2026-Q1 |
| Diversified Investment Strategies, LLC added | 140,000 | $1M | 0.3% | 2026-Q1 |
| FRANKLIN RESOURCES INC added | 138,180 | $1M | 0.3% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC trimmed | 86,059 | $1M | 0.3% | 2026-Q2 |
| AMERIPRISE FINANCIAL INC trimmed | 134,001 | $1M | 0.3% | 2026-Q1 |
| Point72 Asset Management, L.P. added | 79,362 | $1M | 0.3% | 2026-Q2 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. trimmed | 120,752 | $988K | 0.3% | 2026-Q1 |
| Man Group plc added | 117,730 | $963K | 0.3% | 2026-Q1 |
| Bank of New York Mellon Corp trimmed | 113,309 | $927K | 0.3% | 2026-Q1 |
| AMERICAN CENTURY COMPANIES INC trimmed | 112,272 | $918K | 0.3% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ trimmed | 95,430 | $781K | 0.2% | 2026-Q1 |
| HSBC HOLDINGS PLC added | 90,319 | $747K | 0.2% | 2026-Q1 |
| GSA CAPITAL PARTNERS LLP added | 89,051 | $728K | 0.2% | 2026-Q1 |
| Nuveen, LLC added | 82,933 | $678K | 0.2% | 2026-Q1 |
| DEUTSCHE BANK AG\ trimmed | 82,062 | $671K | 0.2% | 2026-Q1 |
| UBS Group AG trimmed | 78,580 | $643K | 0.2% | 2026-Q1 |
| VICTORY CAPITAL MANAGEMENT INC added | 77,232 | $632K | 0.2% | 2026-Q1 |
| BARCLAYS PLC trimmed | 76,906 | $629K | 0.2% | 2026-Q1 |
| Cardinal Point Capital Management ULC added | 71,500 | $585K | 0.2% | 2026-Q1 |
| D. E. Shaw & Co., Inc. trimmed | 44,320 | $581K | 0.2% | 2026-Q2 |
| XTX Topco Ltd added | 68,458 | $560K | 0.2% | 2026-Q1 |
| PUBLIC EMPLOYEES RETIREMENT SYSTEM OF OHIO | 66,426 | $543K | 0.2% | 2026-Q1 |
| Russell Investments Group, Ltd. added | 66,291 | $542K | 0.2% | 2026-Q1 |
| GROUP ONE TRADING LLC added | 63,837 | $522K | 0.2% | 2026-Q1 |
| WELLS FARGO & COMPANY/MN trimmed | 60,747 | $497K | 0.1% | 2026-Q1 |
| CANADA PENSION PLAN INVESTMENT BOARD added | 59,400 | $486K | 0.1% | 2026-Q1 |
| Avestar Capital, LLC trimmed | 55,000 | $450K | 0.1% | 2026-Q1 |
| VOYA INVESTMENT MANAGEMENT LLC added | 53,332 | $436K | 0.1% | 2026-Q1 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 32,040 | $421K | 0.1% | 2026-Q2 |
| Magnetar Financial LLC added | 50,026 | $409K | 0.1% | 2026-Q1 |
| RHUMBLINE ADVISERS trimmed | 49,753 | $407K | 0.1% | 2026-Q1 |
| Creative Planning added | 48,249 | $395K | 0.1% | 2026-Q1 |
| FOX RUN MANAGEMENT, L.L.C. trimmed | 46,673 | $379K | 0.1% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. | 36,200 | $321K | 0.1% | 2026-Q1 |
| IMC-Chicago, LLC added | 36,842 | $301K | 0.1% | 2026-Q1 |
| FULLER & THALER ASSET MANAGEMENT, INC. added | 36,736 | $300K | 0.1% | 2026-Q1 |
| VANGUARD GROUP INC trimmed | 2,379,185 | $21M | 6.3% | 2025-Q4 stale |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 1,170,952 | $10M | 3.1% | 2025-Q4 stale |
| Nixon Capital, LLC added | 628,753 | $6M | 1.7% | 2025-Q1 stale |
| NORDEA INVESTMENT MANAGEMENT AB added | 346,047 | $4M | 1.3% | 2025-Q2 stale |
| Acuitas Investments, LLC added | 355,651 | $3M | 0.9% | 2025-Q3 stale |
| ALGERT GLOBAL LLC added | 314,634 | $3M | 0.8% | 2025-Q4 stale |
| Pacer Advisors, Inc. new | 268,637 | $2M | 0.7% | 2025-Q1 stale |
| Roubaix Capital, LLC new | 271,335 | $2M | 0.7% | 2025-Q3 stale |
| Manatuck Hill Partners, LLC new | 200,000 | $2M | 0.5% | 2025-Q3 stale |
| TWO SIGMA ADVISERS, LP added | 182,600 | $2M | 0.5% | 2025-Q4 stale |
| Walleye Capital LLC added | 156,573 | $1M | 0.4% | 2025-Q4 stale |
| MARSHALL WACE, LLP added | 145,345 | $1M | 0.4% | 2025-Q4 stale |
| Cubist Systematic Strategies, LLC added | 106,523 | $974K | 0.3% | 2025-Q1 stale |
| Apis Capital Advisors, LLC new | 77,500 | $964K | 0.3% | 2025-Q2 stale |
| Schonfeld Strategic Advisors LLC new | 107,854 | $957K | 0.3% | 2025-Q4 stale |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 62,165 | $773K | 0.2% | 2025-Q2 stale |
| Dynamic Technology Lab Private Ltd added | 73,523 | $652K | 0.2% | 2025-Q4 stale |
| Connor, Clark & Lunn Investment Management Ltd. added | 77,044 | $638K | 0.2% | 2025-Q3 stale |
| ExodusPoint Capital Management, LP trimmed | 69,654 | $618K | 0.2% | 2025-Q4 stale |
| Swiss National Bank | 73,200 | $606K | 0.2% | 2025-Q3 stale |
| ARDSLEY ADVISORY PARTNERS LP new | 35,000 | $435K | 0.1% | 2025-Q2 stale |
| Amundi new | 34,101 | $432K | 0.1% | 2025-Q2 stale |
| AlphaQuest LLC trimmed | 47,715 | $423K | 0.1% | 2025-Q4 stale |
| PharVision Advisers, LLC new | 45,735 | $406K | 0.1% | 2025-Q4 stale |
| Qube Research & Technologies Ltd trimmed | 32,508 | $404K | 0.1% | 2025-Q2 stale |
| Inspire Investing, LLC trimmed | 31,015 | $386K | 0.1% | 2025-Q2 stale |
| Janney Montgomery Scott LLC new | 41,503 | $379K | 0.1% | 2025-Q1 stale |
| Counterpoint Mutual Funds LLC added | 43,429 | $360K | 0.1% | 2025-Q3 stale |
| Nebula Research & Development LLC trimmed | 28,104 | $350K | 0.1% | 2025-Q2 stale |
| Penbrook Management LLC | 35,445 | $324K | 0.1% | 2025-Q2 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.