% 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 IMRN 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 | MORGAN STANLEY | 30,57430,574 | $23,689 | — | TRIM -47% |
| 2 | XTX Topco Ltd | 17,38317,383 | $13,468 | — | ADD 23% |
| 3 | CITADEL ADVISORS LLC | 13,80413,804 | $10,695 | — | TRIM -70% |
| 4 | TWO SIGMA SECURITIES, LLC | 10,90610,906 | $8,450 | — | NEW |
| 5 | RHUMBLINE ADVISERS | 7,3677,367 | $5,708 | — | ADD 64% |
| 6 | BNP PARIBAS FINANCIAL MARKETS | 4,6004,600 | $3,564 | — | TRIM -2% |
| 7 | BlackRock, Inc. | 225225 | $174 | — | NEW |
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 |
|---|---|---|---|---|---|---|---|
| MORGAN STANLEY | — | — | 700 | 18K | 57K | 31K | $23,689 |
| XTX Topco Ltd | — | — | — | 18K | 14K | 17K | $13,468 |
| CITADEL ADVISORS LLC | — | — | — | 20K | 46K | 14K | $10,695 |
| TWO SIGMA SECURITIES, LLC | — | — | — | — | — | 11K | $8,450 |
| RHUMBLINE ADVISERS | 6K | 6K | 6K | 6K | 4K | 7K | $5,708 |
| BNP PARIBAS FINANCIAL MARKETS | — | — | 100 | 1K | 5K | 5K | $3,564 |
| BlackRock, Inc. | — | — | — | — | — | 225 | $174 |
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.
| Biggest buyers | Δ shares | Δ value | |
|---|---|---|---|
| TWO SIGMA SECURITIES, LLC | +10,906 | $8,452 | OPEN |
| XTX Topco Ltd | +3,267 | $2,532 | ADD |
| RHUMBLINE ADVISERS | +2,871 | $2,225 | ADD |
| BlackRock, Inc. | +225 | $174 | OPEN |
| Biggest sellers | Δ shares | Δ value | |
|---|---|---|---|
| CITADEL ADVISORS LLC | −31,978 | $24,783 | TRIM |
| MORGAN STANLEY | −26,807 | $20,775 | TRIM |
| JANE STREET GROUP, LLC | −22,458 | $17,405 | CLOSE |
| Virtu Financial LLC | −11,370 | $8,812 | CLOSE |
| UBS Group AG | −4,143 | $3,211 | CLOSE |
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 | 7 | 84,859 | — | $65,748 |
| 2025-Q4 | 9 | 164,456 | — | $125,723 |
| 2025-Q3 | 7 | 64,910 | — | $123,763 |
| 2025-Q2 | 5 | 23,044 | — | $40,095 |
| 2025-Q1 | 3 | 6,099 | — | $10,799 |
| 2024-Q4 | 1 | 5,939 | — | $10,452 |
| 2024-Q3 | 3 | 10,772 | — | $29,240 |
| 2024-Q2 | 4 | 11,468 | — | $28,088 |
| 2024-Q1 | 7 | 40,461 | — | $104,666 |
| 2023-Q4 | 4 | 10,982 | — | $20,593 |
| 2023-Q3 | 4 | 7,891 | — | $15,624 |
| 2023-Q2 | 4 | 11,792 | — | $23,820 |
| 2023-Q1 | 6 | 92,790 | — | $171,508 |
| 2022-Q4 | 7 | 95,296 | — | $198,216 |
| 2022-Q3 | 3 | 20,408 | — | $42,105 |
| 2022-Q2 | 4 | 6,231 | — | $13,319 |
| 2022-Q1 | 10 | 167,138 | — | $311,048 |
| 2021-Q4 | 8 | 234,756 | — | $488,500 |
| 2021-Q3 | 5 | 184,912 | — | $729,000 |
| 2021-Q2 | 5 | 214,618 | — | $430,000 |
| 2021-Q1 | 7 | 237,828 | — | $1M |
| 2020-Q4 | 5 | 197,229 | — | $1M |
| 2020-Q3 | 7 | 216,110 | — | $2M |
| 2020-Q2 | 6 | 157,416 | — | $1M |
| 2020-Q1 | 5 | 115,177 | — | $207,000 |
| 2019-Q4 | 6 | 128,392 | — | $466,000 |
| 2019-Q3 | 6 | 122,263 | — | $364,000 |
| 2019-Q2 | 4 | 108,277 | — | $346,000 |
| 2019-Q1 | 5 | 119,725 | — | $659,000 |
| 2018-Q4 | 5 | 120,323 | — | $646,000 |
| 2018-Q3 | 5 | 121,435 | — | $1M |
| 2018-Q2 | 5 | 125,507 | — | $1M |
| 2018-Q1 | 4 | 135,022 | — | $1M |
| 2017-Q4 | 4 | 87,138 | — | $330,000 |
| 2017-Q3 | 3 | 89,760 | — | $144,000 |
| 2017-Q2 | 3 | 46,420 | — | $152,000 |
