Insider transactions

Atlas Venture Opportunity Fund I, L.P.

CIK 1759241 · last filed 2022-11-01

Atlas Venture Opportunity Fund I, L.P. is a corporate insider who has filed 78 SEC Form 4 insider transactions across 6 companies since 2019. The most recent filing, for IRON, was dated Sep 4, 2026. Across all open-market trades the lifetime net is −$54.6M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $708.5M across reported positions. The firm reports its address in Cambridge, MA. 45 SEC filings were submitted jointly with Atlas Venture Associates Opportunity I, LLC.

"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
$708.45M
Companies
6
Total Filings
78
Lifetime Open-Market Net
-$54.65M

Charts

Trading activity, where the exposure sits, and each trade against the stock price.

Filer Profile

Reported Address
400 TECHNOLOGY SQUARE, 10TH FLOOR
CAMBRIDGE, MA 02139
Phone
(857) 201-2700
State of Incorporation
DE
Related Filers
Atlas Venture Associates Opportunity I, LLC — 45 joint filings, latest 2026-02-09
Atlas Venture Associates Opportunity I, L.P. — 42 joint filings, latest 2026-02-09
ATLAS VENTURE ASSOCIATES X, L.P. — 23 joint filings, latest 2026-02-09
Atlas Venture Associates X, LLC — 23 joint filings, latest 2026-02-09
Atlas Venture Fund X, L.P. — 22 joint filings, latest 2026-02-09
Atlas Venture Fund XI, L.P. — 20 joint filings, latest 2024-02-28
Atlas Venture Associates XI, L.P. — 17 joint filings, latest 2024-02-28
Atlas Venture Associates XI, LLC — 17 joint filings, latest 2024-02-28
Profile details as reported on the filer's SEC submissions — for individual insiders the address is often in care of the issuer. Related filers are identified from jointly filed SEC submissions and shared reported addresses. View filings on SEC EDGAR.

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 6,784,648 $104.35 $707.98M -$52.41M 1 2022-11-01
Day One Biopharmaceuticals, Inc. (DAWN) Delisted 10%+ Owner 793,116 $21.53 $17.08M $0 1 2022-07-06
XLO 10%+ Owner 52,567 $9.07 $476.8K $6.00M 1 2021-10-26
Generation Bio Co. (GBIO) Delisted 10%+ Owner 711,194 $5.34 $3.80M -$8.24M 1 2021-09-29
ImageneBio, Inc. (IKNA) Delisted 10%+ Owner 241,801 $17.16 $4.15M $0 1 2021-04-01
Akero Therapeutics, Inc. (AKRO) Delisted 10%+ Owner 404,079 $54.65 $22.08M $0 2 2020-02-10

Recent Filings

78 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
2026-09-04 IRON Notice (144) −912 -$72.4K EDGAR
2026-09-03 IRON Notice (144) −2,810 -$224.9K EDGAR
2026-08-14 DYN Notice (144) −322,465 -$8.37M EDGAR
2026-08-13 DYN Notice (144) −63,643 -$1.67M EDGAR
2026-07-07 DYN Notice (144) −60,858 -$1.39M EDGAR
2026-07-06 DYN Notice (144) −100,019 -$2.31M EDGAR
2026-06-29 KYMR Notice (144) −10,473 -$1.13M EDGAR
2026-06-29 DYN Notice (144) −40,702 -$852.3K EDGAR
2026-06-26 DYN Notice (144) −64,411 -$1.33M EDGAR
2026-06-26 KYMR Notice (144) −57,451 -$6.69M EDGAR
Showing 1–10 of 78
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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.