% of shares outstanding is not shown for MULL: this is a fund line, and we hold no cover-page share count for it at any quarter — a fund's shares outstanding move with creations and redemptions rather than with issuance and buybacks, and it is not the SEC cover-page count this percentage is defined against. The figure is withheld rather than computed against a count that does not exist. Holder share counts are shown as filed.
Crowding percentile withheld — no market cap for MULL in the served universe — the cohort is size-matched, and an unmatched percentile would compare a micro-cap register to a mega-cap one.
| # | Holder | Shares | Value | % of shares out | Δ QoQ |
|---|---|---|---|---|---|
| 1 | CITADEL ADVISORS LLC | 56,98856,988 | $6M | — | ADD 351% |
| 2 | SIMPLEX TRADING, LLC | 10,74710,747 | $1M | — | NEW |
| 3 | Optiver Holding B.V. | 10,71910,719 | $1M | — | ADD 1046% |
| 4 | BARCLAYS PLC | 10,06010,060 | $1M | — | NEW |
| 5 | MIRAE ASSET SECURITIES (USA) INC. | 10,00010,000 | $1M | — | NEW |
| 6 | JANE STREET GROUP, LLC | 3,8953,895 | $414,272 | — | NEW |
| 7 | SBI Securities Co., Ltd. | 3,0193,019 | $321,101 | — | ADD 748% |
| 8 | Jump Financial, LLC | 2,5902,590 | $275,473 | — | NEW |
| 9 | Csenge Advisory Group | 2,5002,500 | $265,900 | — | NEW |
| 10 | Belvedere Trading LLC | 752752 | $79,983 | — | TRIM -88% |
| 11 | GROUP ONE TRADING LLC | 386386 | $41,055 | — | NEW |
| 12 | UBS Group AG | 120120 | $12,763 | — | TRIM -49% |
| 13 | HOLLENCREST CAPITAL MANAGEMENT | 102102 | $10,849 | — | TRIM -90% |
| 14 | MORGAN STANLEY | 33 | $319 | — | TRIM -40% |
Rows rank by the value each filer reported — 13F filers price their own positions, so a holder with fewer shares can rank just above one with more.
| Holder | 2024-Q4 | 2025-Q1 | 2025-Q2 | 2025-Q3 | 2025-Q4 | 2026-Q1 | Latest value |
|---|---|---|---|---|---|---|---|
| CITADEL ADVISORS LLC | — | — | — | — | 13K | 57K | $6M |
| SIMPLEX TRADING, LLC | 2 | — | — | 328 | — | 11K | $1M |
| Optiver Holding B.V. | — | — | 15K | 17K | 935 | 11K | $1M |
| BARCLAYS PLC | — | — | — | — | — | 10K | $1M |
| MIRAE ASSET SECURITIES (USA) INC. | — | — | — | — | — | 10K | $1M |
| JANE STREET GROUP, LLC | — | — | — | — | — | 4K | $414,272 |
| SBI Securities Co., Ltd. | 1K | 124 | 142 | 60 | 356 | 3K | $321,101 |
| Jump Financial, LLC | — | — | — | — | — | 3K | $275,473 |
| Csenge Advisory Group | — | — | — | — | — | 3K | $265,900 |
| Belvedere Trading LLC | — | — | — | 9K | 6K | 752 | $79,983 |
| GROUP ONE TRADING LLC | — | — | — | — | — | 386 | $41,055 |
| UBS Group AG | — | 2K | — | — | 235 | 120 | $12,763 |
| HOLLENCREST CAPITAL MANAGEMENT | — | — | — | — | 1K | 102 | $10,849 |
| MORGAN STANLEY | — | — | — | — | 5 | 3 | $319 |
Shares reported each quarter by the largest current holders. Green = added vs the prior filing, red = trimmed, grey = roughly held; a dash is a quarter with no 13F on file (a gap is skipped, not read as an exit). 13F is filed up to 45 days after quarter-end. Up to 40 quarters (10 years) available — use the selector above.
Holder count only — too few computable %-of-shares-outstanding quarters for a % pane. Line breaks are quarters with no 13F record, never interpolated.
| Quarter | Holders | Shares held | % shares out | Value held |
|---|---|---|---|---|
| 2026-Q1 | 14 | 111,881 | — | $12M |
| 2025-Q4 | 8 | 42,484 | — | $4M |
| 2025-Q3 | 5 | 35,611 | — | $1M |
| 2025-Q2 | 3 | 15,765 | — | $337,844 |
| 2025-Q1 | 2 | 2,578 | — | $32,973 |
| 2024-Q4 | 3 | 31,887 | — | $435,957 |
Short interest has its own tab now — open SI →
Source: SEC Form 13F — every institution manager (≥ $100M in 13F securities) reporting a long US-listed position, across ~10,250 filers over 10 years of history. 13F is long-only, US-listed, filed up to 45 days after quarter-end.
| Biggest buyers | Δ shares | Δ value | |
|---|---|---|---|
| CITADEL ADVISORS LLC | +44,348 | $5M | ADD |
| SIMPLEX TRADING, LLC | +10,747 | $1M | OPEN |
| BARCLAYS PLC | +10,060 | $1M | OPEN |
| MIRAE ASSET SECURITIES (USA) INC. | +10,000 | $1M | OPEN |
| Optiver Holding B.V. | +9,784 | $1M | ADD |
| Biggest sellers | Δ shares | Δ value | |
|---|---|---|---|
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | −21,161 | $2M | CLOSE |
| Belvedere Trading LLC | −5,397 | $574,025 | TRIM |
| HOLLENCREST CAPITAL MANAGEMENT | −901 | $95,830 | TRIM |
| UBS Group AG | −115 | $12,231 | TRIM |
| MORGAN STANLEY | −2 | $213 | TRIM |
The 2025-Q4 register is as-filed in ITS OWN share basis; every count below was rebased into the 2026-Q1 basis (no split in between, factor 1). Dollar figures value the SHARE delta at one price — the 2026-03-31 close — rather than differencing two filings' own reported values, which would mix the quarter's price move into the trade figure.
13Fs disclose LONG US-listed positions only — shorts, most derivatives, bonds and non-US listings are invisible here, and a filer's quarter-over-quarter change is not necessarily a trade (index rebalances, in-kind transfers and entity successions all read as flow).
