Atlas Venture Fund X, L.P.
CIK 1628098 · last filed 2024-01-25
"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
$846.77M
Companies
6
Total Filings
65
Lifetime Open-Market Net
-$46.33M
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 |
|---|---|---|---|---|---|---|---|
| IRON | 10%+ Owner | 2,105,846 | $81.92 | $172.51M | -$91.33M | 1 | 2024-01-25 |
| Generation Bio Co. (GBIO) Delisted | 10%+ Owner | 827,888 | $5.34 | $4.42M | $0 | 4 | 2021-09-21 |
| KYMR | 10%+ Owner | 5,763,012 | $110.53 | $636.96M | $0 | 2 | 2021-05-18 |
| Dianthus Therapeutics, Inc. /DE/ (MGTA) Delisted | 10%+ Owner | 196,775 | $11.19 | $2.20M | $0 | 2 | 2021-02-16 |
| REPL | 10%+ Owner | 2,486,296 | $15.01 | $37.31M | $0 | 4 | 2020-09-17 |
| Tectonic Therapeutic, Inc. (AVRO) Delisted | 10%+ Owner | 396,373 | $16.80 | $6.66M | $45.00M | 2 | 2019-07-29 |
Recent Filings · Page 4 of 7
65 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 |
|---|---|---|---|---|---|
| 2025-07-18 | IRON | Notice (144) | −1,184 | -$68.4K | EDGAR |
| 2025-02-05 | IRON | Notice (144) | −112,211 | -$6.10M | EDGAR |
| 2025-02-04 | IRON | Notice (144) | −6,350 | -$349.2K | EDGAR |
| 2025-02-03 | IRON | Notice (144) | −6,439 | -$359.3K | EDGAR |
| 2024-07-09 | KYMR | Notice (144) | −375,184 | -$11.99M | EDGAR |
| 2024-06-13 | KYMR | Notice (144) | −8,430 | -$291.7K | EDGAR |
| 2024-06-12 | KYMR | Notice (144) | −13,835 | -$478.3K | EDGAR |
| 2024-03-15 | KYMR | Notice (144) | −59,310 | -$2.34M | EDGAR |
| 2024-03-14 | KYMR | Notice (144) | −46,100 | -$1.95M | EDGAR |
| 2024-03-13 | KYMR | Notice (144) | −115,090 | -$4.82M | 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.