As of November 9, 2026, 2 holders' latest Schedule 13D or 13G filings report owning 5% or more of Mayville Engineering Co Inc. The largest reported stake is BlackRock, Inc.'s, at 6.3%. 8 filings are on record since October 29, 2025 (Schedule 13G, October 27, 2026).
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Key facts
- · Reporting person: Fmr LLC · Sole voting: 844,040 · Shared voting: 0 · Sole dispositive: 846,181 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-11-05
- · Reporting person: BlackRock, Inc. · Sole voting: 1,568,893 · Shared voting: 0 · Sole dispositive: 1,605,585 · Shared dispositive: 0 · SCHEDULE 13G, 2026-10-27
- · Holder: Fmr LLC · Percent: 5% · SCHEDULE 13G
- · Reporting person: Allspring Global Investments Holdings, LLC · Sole voting: 1,072,306 · Shared voting: 0 · Sole dispositive: 1,072,916 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-07-08
- · Holder: Portolan Capital Management, LLC · Percent: 5.92% · SCHEDULE 13G
Mayville Engineering Co Inc has 8 Schedule 13D or 13G filings on record since 2025-10-29. 2 holders' latest filing reports 5% or more of common stock. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| BlackRock, Inc. | 6.3% | 1,605,585 | SCHEDULE 13G, 2026-10-27 | 2026-09-30 |
| Portolan Capital Management, LLC | 5.92% | 1,465,004 | SCHEDULE 13G, 2026-05-28 | 2026-05-20 |
| Hilve Holdings Ltd | 4.9% | 995,756 | SCHEDULE 13G/A, 2026-02-13 | 2025-10-27 |
| Allspring Global Investments Holdings, LLC | 4.2% | 1,072,916 | SCHEDULE 13G/A, 2026-07-08 | 2026-06-30 |
| Fmr LLC | 3.3% | 846,181 | SCHEDULE 13G/A, 2026-11-05 | 2026-09-30 |
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Keep reading
More on Mayville Engineering Co Inc and the records around it.
Mayville Engineering Co Inc elsewhere on the record
Companies that share a holder
- Hilve Holdings Ltd also filed stake reports on 2 other companies: BK Technologies Corp (May 2026), electroCore, Inc. (May 2026)
- Portolan Capital Management, LLC also filed stake reports on 13 other companies: LANTRONIX, INC. (Oct 2026), SILICOM LTD. (Sep 2026), Quanterix Corp (Aug 2026)
- Allspring Global Investments Holdings, LLC also filed stake reports on 49 other companies: abrdn Emerging Markets ex Chin (Oct 2026), AMC Global Media Inc (Oct 2026), EverQuote Inc (Oct 2026)
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What the Full Report on Mayville Engineering Co Inc covers
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| BlackRock, Inc. | 1,568,893 | 0 | 1,605,585 | 0 | SCHEDULE 13G, 2026-10-27 |
| Allspring Global Investments Holdings, LLC | 1,072,306 | 0 | 1,072,916 | 0 | SCHEDULE 13G/A, 2026-07-08 |
| Fmr LLC | 844,040 | 0 | 846,181 | 0 | SCHEDULE 13G/A, 2026-11-05 |
| Abigail P. Johnson | 0 | 0 | 846,181 | 0 | SCHEDULE 13G/A, 2026-11-05 |
The latest filing identifies Mayville Engineering Co Inc by CUSIP 578605107 and gives its principal executive office as 715 SOUTH STREET, MAYVILLE, WI 53050 (SCHEDULE 13G/A, 2026-11-05).
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-10-29 | Hilve Holdings Ltd | 5.3% | SCHEDULE 13G |
| 2026-01-08 | Allspring Global Investments Holdings, LLC | 10.1% | SCHEDULE 13G/A |
| 2026-02-13 | Hilve Holdings Ltd | 4.9% | SCHEDULE 13G/A |
| 2026-05-28 | Portolan Capital Management, LLC | 5.92% | SCHEDULE 13G |
| 2026-07-08 | Allspring Global Investments Holdings, LLC | 4.2% | SCHEDULE 13G/A |
| 2026-08-06 | Fmr LLC | 5% | SCHEDULE 13G |
| 2026-10-27 | BlackRock, Inc. | 6.3% | SCHEDULE 13G |
| 2026-11-05 | Fmr LLC | 3.3% | SCHEDULE 13G/A |
Questions about who owns Mayville Engineering Co Inc
Who owns Mayville Engineering Co Inc?
On this page, 2 holders' latest ownership filings report 5% or more of Mayville Engineering Co Inc: BlackRock, Inc. (6.3%, Schedule 13G, filed 2026-10-27) and Portolan Capital Management, LLC (5.92%, Schedule 13G, filed 2026-05-28).
Who are the largest shareholders of Mayville Engineering Co Inc?
By the share each holder's latest filing reports, the largest holders of Mayville Engineering Co Inc on this page are BlackRock, Inc. (6.3%) and Portolan Capital Management, LLC (5.92%).
When did BlackRock, Inc. buy into Mayville Engineering Co Inc?
The filings give report dates, not purchase dates. The earliest filing from BlackRock, Inc. on this page is the Schedule 13G, filed 2026-10-27, reporting 6.3%.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 8 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.