JANE STREET GROUP, LLC
Position in MEC — Mayville Engineering Company, Inc.
CIK 1595888
NEW YORK, NY
Position in MEC
as of Jun 30, 2026
· filed Aug 14, 2026
Position Value
$13,341,415
+$12,347,870 QoQ
Shares Held
356,151
+571.0% QoQ
Ownership
1.40%
of shares outstanding
% of Portfolio
0.01%
of 13F equity value
Holder Rank
#17
of 153 holders
Holding Since
Dec 2020
10 quarters on record
Voting authority
Sole 100%
Shared 0%
None 0%
Common Shares in MEC Over Time
Shares Held
Position Value (USD)
Derivatives in MEC
reported options exposure · as of Jun 30, 2026CallValue
$1,015,166
CallShares
27,100
PutValue
$752,946
PutShares
20,100
Notional value of option positions as reported on Form 13F. Calls and puts are disclosed separately and do not net against the common-share stake above.
Position in Metal Fabrication
Industrials · as of Jun 30, 2026JANE STREET GROUP, LLC holds $550,159,095 across 11 Metal Fabrication names. MEC ranks #3 (2.4% of the industry book) .
| # | Ticker | Company | Shares | Value (USD) | Open |
|---|---|---|---|---|---|
| 1 | ATI |
Ati Inc
|
1,410,930 | $278,094,302 | |
| 2 | CRS |
Carpenter Technology Corp
|
356,156 | $219,691,266 | |
| 3 | MEC |
Mayville Engineering Company, Inc.
This page
|
356,151 | $13,341,415 | |
| 4 | IIIN |
Insteel Industries Inc
|
438,799 | $13,251,729 | |
| 5 | PRLB |
Proto Labs Inc
|
143,527 | $11,698,884 | |
| 6 | CMC |
COMMERCIAL METALS Co
|
84,544 | $5,305,135 | |
| 7 | WOR |
Worthington Enterprises, Inc.
|
95,565 | $5,137,574 | |
| 8 | AP |
Ampco Pittsburgh Corp
|
150,371 | $1,300,708 |
All Filings in MEC
Export CSV
14 filing rows on record
| Report Date | Value (USD) | Shares | Type | Discretion | Filed | |
|---|---|---|---|---|---|---|
| 2026-06-30 | $1,015,166 | 27,100 | Call | Defined | 2026-08-14 | |
| 2026-06-30 | $752,946 | 20,100 | Put | Defined | 2026-08-14 | |
| 2026-06-30 | $13,341,415 | 356,151 | Shares | Defined | 2026-08-14 | |
| 2025-12-31 | $438,048 | 23,400 | Call | Defined | 2026-02-12 | |
| 2025-12-31 | $993,545 | 53,074 | Shares | Defined | 2026-02-12 | |
| 2025-12-31 | $419,328 | 22,400 | Put | Defined | 2026-02-12 | |
| 2025-09-30 | $257,724 | 18,730 | Shares | Defined | 2025-11-14 | |
| 2025-03-31 | $633,815 | 47,194 | Shares | Defined | 2025-05-19 | |
| 2024-12-31 | $286,858 | 18,248 | Shares | Defined | 2025-02-14 | |
| 2024-09-30 | $300,073 | 14,235 | Shares | Defined | 2024-11-15 | |
| 2024-06-30 | $188,690 | 11,326 | Shares | Defined | 2024-08-15 | |
| 2023-06-30 | $318,726 | 25,580 | Shares | Defined | 2023-08-14 | |
| 2023-03-31 | $791,834 | 53,072 | Shares | Defined | 2023-05-16 | |
| 2020-12-31 | $135,193 | 10,074 | Shares | Defined | 2021-02-17 | |
| No filing history on record for this holder in this stock. | ||||||