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ATLAS VENTURE ASSOCIATES X, L.P.

CIK 1742766 · last filed 2024-03-13

ATLAS VENTURE ASSOCIATES X, L.P. is a corporate insider who has filed 12 SEC Form 4 insider transactions across 6 companies since 2018. The most recent filing shows the insider sold $89.5M of KYMR on Mar 13, 2024. Across all open-market trades the lifetime net is −$383.0M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $888.6M across reported positions.

"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

$888.55M

Companies

6

Total Filings

12

Lifetime Open-Market Net

-$382.95M

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 10%+ Owner 5,812,200 $109.62 $637.13M -$184.55M 5 2024-03-13
IRON 10%+ Owner 2,347,367 $81.21 $190.63M -$183.18M 2 2023-12-14
Generation Bio Co. (GBIO) Delisted 10%+ Owner 911,194 $5.34 $4.87M -$14.46M 2 2021-04-14
Tectonic Therapeutic, Inc. (AVRO) Delisted 10%+ Owner 309,171 $16.80 $5.19M $0 1 2020-02-18
Dianthus Therapeutics, Inc. /DE/ (MGTA) Delisted 10%+ Owner 257,320 $11.19 $2.88M -$763.2K 1 2019-03-22
REPL 10%+ Owner 4,453,386 $13.65 $60.79M $0 1 2018-07-26

Recent Filings

12 filings
Insider 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
2024-03-13 KYMR Sell (S) −2,120,142 -$89.47M EDGAR
2023-12-14 IRON Sell (S) −1,140,978 -$70.11M EDGAR
2023-08-16 IRON Sell (S) −2,154,000 -$113.07M EDGAR
2022-11-04 KYMR Sell (S) −1,320,096 -$39.62M EDGAR
2021-08-12 KYMR Sell (S) −484,266 -$29.54M EDGAR
2021-04-14 Generation Bio Co. (GBIO) Delisted Sell (S) −281,364 -$7.29M EDGAR
2021-04-09 Generation Bio Co. (GBIO) Delisted Sell (S) −254,190 -$7.17M EDGAR
2021-03-16 KYMR Sell (S) −458,700 -$25.92M EDGAR
2020-08-25 KYMR Conv (C) +49,855,620 $0 EDGAR
2020-02-18 Tectonic Therapeutic, Inc. (AVRO) Delisted Other (J) −1,046,426 $0 EDGAR
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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.