Who owns Mayville Engineering Company (MEC)
Which tracked institutional funds hold MEC, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MEC 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.
How the tape is positioned
The tracked-fund tape on MEC is one-sided between 2026-Q1 and 2026-Q2: 86 added or opened and 13 trimmed or exited — on balance accumulating.
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
MEC’s largest tracked holder by dollar value, Portolan Capital Management, LLC, sizes it at 1.8% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 1.8pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MEC 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 145 tracked filers holding MEC, 90 increased or opened the position and 66 reduced or closed it; over the same quarter, open-market insider Form 4s were net sales.
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 MEC 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 26
- Driehaus Capital Management LLC$32M
- SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC$30M
- Jupiter Topco LLC$22M
- WELLINGTON MANAGEMENT GROUP LLP$18M
- JANE STREET GROUP, LLC$13M
- Ophir Asset Management Pty Ltd$12M
Full exits 10
- AMERIPRISE FINANCIAL INC$6M
- Roubaix Capital, LLC$4M
- ARROWSTREET CAPITAL, LIMITED PARTNERSHIP$3M
- Integrated Quantitative Investments LLC$909K
- HighTower Advisors, LLC$800K
- JOURNEY STRATEGIC WEALTH LLC$793K
Largest adds
- FMR LLC$48M
- Portolan Capital Management, LLC$34M
- BlackRock, Inc.$29M
- Boston Partners$22M
- VANGUARD CAPITAL MANAGEMENT LLC$17M
- ROYCE & ASSOCIATES LP$15M
Largest trims
- AMERICAN CENTURY COMPANIES INC$2M
- CenterBook Partners LP$998K
- OSAIC HOLDINGS, INC.$295K
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.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| Portolan Capital Management, LLC added | 1,299,256 | $49M | 6.3% | 2026-Q2 |
| FMR LLC added | 1,280,170 | $48M | 6.2% | 2026-Q2 |
| BlackRock, Inc. added | 1,183,443 | $44M | 5.7% | 2026-Q2 |
| Allspring Global Investments Holdings, LLC trimmed | 1,072,916 | $38M | 4.9% | 2026-Q2 |
| Driehaus Capital Management LLC new | 846,354 | $32M | 4.1% | 2026-Q2 |
| SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC new | 800,000 | $30M | 3.9% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP trimmed | 782,276 | $29M | 3.8% | 2026-Q2 |
| ROYCE & ASSOCIATES LP added | 752,083 | $28M | 3.7% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 743,621 | $28M | 3.6% | 2026-Q2 |
| Boston Partners added | 696,429 | $26M | 3.3% | 2026-Q2 |
| Jupiter Topco LLC new | 575,278 | $22M | 2.8% | 2026-Q2 |
| BLAIR WILLIAM & CO/IL trimmed | 546,714 | $20M | 2.7% | 2026-Q2 |
| WELLINGTON MANAGEMENT GROUP LLP new | 477,583 | $18M | 2.3% | 2026-Q2 |
| EVR Research LP trimmed | 441,908 | $17M | 2.1% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 374,578 | $14M | 1.8% | 2026-Q2 |
| First Eagle Investment Management, LLC trimmed | 369,575 | $14M | 1.8% | 2026-Q2 |
| JANE STREET GROUP, LLC added | 356,151 | $13M | 1.7% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 347,224 | $13M | 1.7% | 2026-Q2 |
| KENNEDY CAPITAL MANAGEMENT LLC added | 336,377 | $13M | 1.6% | 2026-Q2 |
| Ophir Asset Management Pty Ltd new | 326,699 | $12M | 1.6% | 2026-Q2 |
| Granahan Investment Management, LLC trimmed | 324,108 | $12M | 1.6% | 2026-Q2 |
| SILVERCREST ASSET MANAGEMENT GROUP LLC added | 313,943 | $12M | 1.5% | 2026-Q2 |
| STATE STREET CORP added | 291,168 | $11M | 1.4% | 2026-Q2 |
| Nuveen, LLC added | 281,914 | $11M | 1.4% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ added | 276,317 | $10M | 1.3% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 253,677 | $10M | 1.2% | 2026-Q2 |
| JB CAPITAL PARTNERS LP | 250,512 | $9M | 1.2% | 2026-Q2 |
| Squarepoint Ops LLC added | 238,766 | $9M | 1.2% | 2026-Q2 |
| CONGRUENCE CAPITAL, LLC added | 235,580 | $9M | 1.1% | 2026-Q2 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC trimmed | 200,980 | $8M | 1.0% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP added | 198,912 | $7M | 1.0% | 2026-Q2 |
| CITADEL ADVISORS LLC added | 198,712 | $7M | 1.0% | 2026-Q2 |
| AWM Investment Company, Inc. new | 180,000 | $7M | 0.9% | 2026-Q2 |
| OSTERWEIS CAPITAL MANAGEMENT INC new | 174,600 | $7M | 0.8% | 2026-Q2 |
| TUDOR INVESTMENT CORP ET AL new | 169,848 | $6M | 0.8% | 2026-Q2 |
| Wealthspire Advisors, LLC | 141,607 | $5M | 0.7% | 2026-Q2 |
| Pillsbury Lake Capital LLC new | 136,746 | $5M | 0.7% | 2026-Q2 |
| Informed Momentum Co LLC added | 129,182 | $5M | 0.6% | 2026-Q2 |
| Russell Investments Group, Ltd. trimmed | 125,513 | $5M | 0.6% | 2026-Q2 |
| SEI INVESTMENTS CO trimmed | 118,607 | $4M | 0.6% | 2026-Q2 |
| Empowered Funds, LLC trimmed | 116,570 | $4M | 0.6% | 2026-Q2 |
| NORTHERN TRUST CORP added | 114,995 | $4M | 0.6% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS added | 112,455 | $4M | 0.5% | 2026-Q2 |
| NEEDHAM INVESTMENT MANAGEMENT LLC added | 110,000 | $4M | 0.5% | 2026-Q2 |
| Trexquant Investment LP added | 100,517 | $4M | 0.5% | 2026-Q2 |
| MORGAN STANLEY added | 100,159 | $4M | 0.5% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 98,709 | $4M | 0.5% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC added | 98,263 | $4M | 0.5% | 2026-Q2 |
| Walleye Capital LLC added | 93,444 | $4M | 0.5% | 2026-Q2 |
| Qube Research & Technologies Ltd added | 87,129 | $3M | 0.4% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 85,462 | $3M | 0.4% | 2026-Q2 |
| UBS Group AG trimmed | 82,662 | $3M | 0.4% | 2026-Q2 |
| ANCHOR CAPITAL ADVISORS LLC trimmed | 80,884 | $3M | 0.4% | 2026-Q2 |
| Invesco Ltd. added | 75,331 | $3M | 0.4% | 2026-Q2 |
| FORMULA GROWTH LTD trimmed | 75,000 | $3M | 0.4% | 2026-Q2 |
| TOCQUEVILLE ASSET MANAGEMENT L.P. | 71,100 | $3M | 0.3% | 2026-Q2 |
| Panoramic Capital, LLC trimmed | 70,000 | $3M | 0.3% | 2026-Q2 |
| XTX Topco Ltd added | 65,604 | $2M | 0.3% | 2026-Q2 |
| POLEN CAPITAL MANAGEMENT LLC new | 61,827 | $2M | 0.3% | 2026-Q2 |
| Essential Investment Partners LLC added | 58,886 | $2M | 0.3% | 2026-Q2 |
| CITIGROUP INC added | 52,620 | $2M | 0.3% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 51,990 | $2M | 0.3% | 2026-Q2 |
| AMERICAN CENTURY COMPANIES INC trimmed | 48,211 | $2M | 0.2% | 2026-Q2 |
| BALYASNY ASSET MANAGEMENT L.P. new | 47,052 | $2M | 0.2% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 45,861 | $2M | 0.2% | 2026-Q2 |
| SummerHaven Investment Management, LLC | 45,325 | $2M | 0.2% | 2026-Q2 |
| Bank of New York Mellon Corp added | 44,873 | $2M | 0.2% | 2026-Q2 |
| GatePass Capital, LLC new | 40,000 | $1M | 0.2% | 2026-Q2 |
| OSAIC HOLDINGS, INC. trimmed | 39,614 | $1M | 0.2% | 2026-Q2 |
| SHEETS SMITH WEALTH MANAGEMENT trimmed | 37,897 | $1M | 0.2% | 2026-Q2 |
| Diametric Capital, LP new | 35,727 | $1M | 0.2% | 2026-Q2 |
| Aquatic Capital Management LLC added | 31,731 | $1M | 0.2% | 2026-Q2 |
| CenterBook Partners LP trimmed | 30,992 | $1M | 0.2% | 2026-Q2 |
| BOOTHBAY FUND MANAGEMENT, LLC added | 30,584 | $1M | 0.1% | 2026-Q2 |
| North Star Investment Management Corp. | 30,000 | $1M | 0.1% | 2026-Q2 |
| KORNITZER CAPITAL MANAGEMENT INC /KS new | 29,587 | $1M | 0.1% | 2026-Q2 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 28,000 | $1M | 0.1% | 2026-Q2 |
| Divisadero Street Capital Management, LP new | 27,482 | $1M | 0.1% | 2026-Q2 |
| Quadrature Capital Ltd new | 26,477 | $992K | 0.1% | 2026-Q2 |
| Johnson Financial Group, Inc. added | 26,000 | $974K | 0.1% | 2026-Q2 |
| PRELUDE CAPITAL MANAGEMENT, LLC new | 23,969 | $898K | 0.1% | 2026-Q2 |
| LPL Financial LLC added | 22,172 | $831K | 0.1% | 2026-Q2 |
| O'SHAUGHNESSY ASSET MANAGEMENT, LLC trimmed | 21,785 | $816K | 0.1% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 20,300 | $760K | 0.1% | 2026-Q2 |
| RHUMBLINE ADVISERS added | 20,001 | $749K | 0.1% | 2026-Q2 |
| ENVESTNET ASSET MANAGEMENT INC trimmed | 18,920 | $709K | 0.1% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC trimmed | 18,224 | $683K | 0.1% | 2026-Q2 |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 18,171 | $681K | 0.1% | 2026-Q2 |
| WESBANCO BANK INC new | 18,000 | $674K | 0.1% | 2026-Q2 |
| DEUTSCHE BANK AG\ added | 14,278 | $535K | 0.1% | 2026-Q2 |
| Caption Management, LLC new | 14,092 | $528K | 0.1% | 2026-Q2 |
| WEALTH ENHANCEMENT ADVISORY SERVICES, LLC added | 13,946 | $470K | 0.1% | 2026-Q2 |
| FRANKLIN RESOURCES INC trimmed | 12,816 | $480K | 0.1% | 2026-Q2 |
| Numerai GP LLC trimmed | 12,410 | $465K | 0.1% | 2026-Q2 |
| Creative Planning new | 12,159 | $455K | 0.1% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ new | 12,026 | $451K | 0.1% | 2026-Q2 |
| US BANCORP \DE\ added | 11,385 | $426K | 0.1% | 2026-Q2 |
| EntryPoint Capital, LLC trimmed | 10,793 | $404K | 0.1% | 2026-Q2 |
| Worth Venture Partners, LLC trimmed | 10,641 | $399K | 0.1% | 2026-Q2 |
| BARCLAYS PLC trimmed | 10,197 | $382K | 0.0% | 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.
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.