Bruce Booth
CIK 1451612 · last filed 2026-07-02
"Disclosed insider exposure" sums this person's most-recently-reported share counts across each company they're an insider in, multiplied by the current underlying price. It is not net worth — it misses retail holdings, private investments, real estate, index funds, and any company where the person isn't an SEC-reporting insider. For informational purposes only.
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Disclosed Exposure
$71.89M
Companies
8
Total Filings
86
Lifetime Open-Market Net
-$248.00M
Holdings By Company
Latest on-record share count from this person's most recent non-derivative Form 4 transaction in each company. Disclosed exposure = shares × current underlying price.
| Symbol | Role | Shares | Price | Disclosed Exposure | Lifetime OM Net | Filings | Latest Filed |
|---|---|---|---|---|---|---|---|
| KYMR | Director | 475,805 | $119.05 | $56.64M | -$263.36M | 27 | 2026-07-02 |
| SION | Director | 2,360,156 | $6.46 | $15.25M | -$21.01M | 8 | 2026-06-18 |
| Vigil Neuroscience, Inc. (VIGL) Delisted | Director | 0 | $8.05 | $0 | $7.49M | 11 | 2025-08-05 |
| Tectonic Therapeutic, Inc. (AVRO) Delisted | Director | 463,941 | $16.80 | $7.79M | $15.00M | 7 | 2023-06-08 |
| Dianthus Therapeutics, Inc. /DE/ (MGTA) Delisted | Director | 257,320 | $11.19 | $2.88M | $9.75M | 7 | 2022-06-30 |
| Cogent Biosciences, Inc. (UMRX) Delisted | Director | 3,184,446 | — | — | $1.13M | 12 | 2020-07-06 |
| Viridian Therapeutics, Inc.\DE (MGEN) Delisted | Director | 209,505 | — | — | $3.00M | 5 | 2018-06-28 |
| Larimar Therapeutics, Inc. (ZFGN) Delisted | Director | 386,502 | — | — | $0 | 7 | 2018-01-05 |
Recent Filings · Page 5 of 9
86 filingsInsider activity across all companies, newest first. Form 4 rows are post-trade confirmations (buys, sells, grants, exercises). Notice (144) rows are pre-trade notices of intent to sell restricted or control stock under Rule 144 — they may not all execute. Compare adjacent dates to see which notices became actual sales.
| Filed | Symbol | Action | Net Shares | Net $ | Link |
|---|---|---|---|---|---|
| 2022-06-30 | Dianthus Therapeutics, Inc. /DE/ (MGTA) Delisted | Grant (A) | — | $0 | EDGAR |
| 2022-06-16 | KYMR | Grant (A) | — | $0 | EDGAR |
| 2022-06-13 | Vigil Neuroscience, Inc. (VIGL) Delisted | Grant (A) | — | $0 | EDGAR |
| 2022-06-10 | Tectonic Therapeutic, Inc. (AVRO) Delisted | Grant (A) | — | $0 | EDGAR |
| 2022-03-03 | Vigil Neuroscience, Inc. (VIGL) Delisted | Grant (A) | — | $0 | EDGAR |
| 2022-01-11 | Vigil Neuroscience, Inc. (VIGL) Delisted | Mixed | +4,394,498 | $7.49M | EDGAR |
| 2021-08-12 | KYMR | Sell (S) | −242,133 | -$14.77M | EDGAR |
| 2021-06-17 | KYMR | Grant (A) | — | $0 | EDGAR |
| 2021-06-14 | Tectonic Therapeutic, Inc. (AVRO) Delisted | Grant (A) | — | $0 | EDGAR |
| 2021-06-03 | Dianthus Therapeutics, Inc. /DE/ (MGTA) Delisted | Grant (A) | — | $0 | EDGAR |
Form 4 codes: P = open-market purchase · S = open-market sale · A = grant/award · M = option exercise · F = tax withholding at vest · G = bona-fide gift · D = disposition to issuer · J = other (see filing footnote). Only P / S codes carry directional signal.
Notice (144 / 144/A): Form 144 is a notice of intent to sell restricted/control stock under Rule 144, filed before the sale; 144/A is an amendment. Many notices are pre-scheduled under Rule 10b5-1 plans. A Form 4 with code S typically follows within a few days when the planned sale executes; missing follow-up Form 4s suggest the notice was cancelled or modified.
Notice (144 / 144/A): Form 144 is a notice of intent to sell restricted/control stock under Rule 144, filed before the sale; 144/A is an amendment. Many notices are pre-scheduled under Rule 10b5-1 plans. A Form 4 with code S typically follows within a few days when the planned sale executes; missing follow-up Form 4s suggest the notice was cancelled or modified.