% of shares outstanding not shown: no SEC cover-page share count falls within 120 days of the 2026-Q1 quarter end, so any percentage would rest on a count that cannot speak for this quarter. Holder share counts are shown as filed.
Crowding percentile withheld — no market cap for MRM 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 | UBS Group AG | 26,54826,548 | $29,734 | — | ADD 634% |
| 2 | TWO SIGMA SECURITIES, LLC | 13,97713,977 | $15,654 | — | NEW |
| 3 | HRT FINANCIAL LP | 11,90511,905 | $13,000 | — | NEW |
| 4 | GAMMA Investing LLC | 6,4096,409 | $7,178 | — | TRIM -39% |
| 5 | RHUMBLINE ADVISERS | 1,9841,984 | $2,222 | — | TRIM -53% |
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 |
|---|---|---|---|---|---|---|---|
| UBS Group AG | 45K | 98K | 33K | — | 4K | 27K | $29,734 |
| TWO SIGMA SECURITIES, LLC | — | — | — | — | — | 14K | $15,654 |
| HRT FINANCIAL LP | — | — | — | — | — | 12K | $13,000 |
| GAMMA Investing LLC | 5K | — | 104 | 5K | 11K | 6K | $7,178 |
| RHUMBLINE ADVISERS | — | — | 1K | 1K | 4K | 2K | $2,222 |
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.
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.
“Item 4 of the Schedule 13D is amended and supplemented to add the following: On July 14, 2026, the Bonds previously held by the Reporting Person were redeemed in full. As a result, the Reporting Person no longer beneficially owns any Common Shares.”
Source: SEC Schedule 13D/13G structured XML. 13D = active intent; 13G filers report passively (Rule 13d-1(b) QII / 13d-1(c) Passive / 13d-1(d) Exempt) and are not activists. Percent and delta are the group aggregate the filing reports. Structured 13D/G coverage begins December 2024 (SEC XML mandate).
| Biggest buyers | Δ shares | Δ value | |
|---|---|---|---|
| UBS Group AG | +22,932 | $25,684 | ADD |
| TWO SIGMA SECURITIES, LLC | +13,977 | $15,654 | OPEN |
| HRT FINANCIAL LP | +11,905 | $13,334 | OPEN |
| Biggest sellers | Δ shares | Δ value | |
|---|---|---|---|
| GAMMA Investing LLC | −4,146 | $4,644 | TRIM |
| RHUMBLINE ADVISERS | −2,269 | $2,541 | 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).
| Quarter | Holders | Shares held | % shares out | Value held |
|---|
| 2026-Q1 | 5 | 60,823 | — | $67,788 |
| 2025-Q4 | 3 | 18,424 | — | $35,743 |
| 2025-Q3 | 4 | 164,369 | — | $348,461 |
| 2025-Q2 | 6 | 72,712 | — | $102,845 |
| 2025-Q1 | 3 | 179,778 | — | $65,964 |
| 2024-Q4 | 5 | 122,150 | — | $126,798 |
| 2024-Q3 | 3 | 29,004 | — | $87,186 |
| 2024-Q2 | 2 | 55 | — | $216 |
| 2024-Q1 | 1 | 407 | — | $2,499 |
| 2023-Q4 | 1 | 25 | — | $143 |
| 2023-Q3 | 2 | 56 | — | $323 |
| 2023-Q1 | 1 | 4 | — | $25 |
| 2022-Q4 | 1 | 1,939 | — | $8,745 |
| 2022-Q3 | 1 | 2,112 | — | $13,000 |
| 2022-Q2 | 1 | 2,105 | — | $13,000 |
| 2022-Q1 | 4 | 15,714 | — | $116,000 |
| 2021-Q4 | 3 | 13,069 | — | $79,000 |
| 2021-Q3 | 5 | 11,864 | — | $101,000 |
| 2021-Q2 | 1 | 68,500 | — | $664,000 |
| 2021-Q1 | 4 | 100,135 | — | $1M |
| 2020-Q4 | 2 | 70,901 | — | $1M |
