Third Rock Ventures GP, L.P.

CIK 1578976 · last filed 2017-10-19

Third Rock Ventures GP, L.P. is a corporate insider who has filed 10 SEC Form 4 insider transactions across 6 companies since 2013. The most recent filing, for CTMX, was dated Oct 19, 2017. Across all open-market trades the lifetime net is −$649.2M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $437.7M 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.

Disclosed Exposure

$437.72M

Companies

6

Total Filings

10

Lifetime Open-Market Net

-$649.17M

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
CTMX	10%+ Owner	116,927	$3.40	$397.6K	$0	1	2017-10-19
RYTM	10%+ Owner	3,981,437	$109.84	$437.32M	$0	1	2017-10-11
Larimar Therapeutics, Inc. (ZFGN) Delisted	10%+ Owner	0	—	—	$0	2	2015-07-24
Foundation Medicine, Inc. (FMI) Delisted	10%+ Owner	828,456	—	—	-$614.82M	2	2015-04-16
AGIO	10%+ Owner	0	$37.90	$0	$0	2	2015-02-19
bluebird bio, Inc. (BLUE) Delisted	10%+ Owner	1,215,054	$4.97	$6.04M	-$34.36M	2	2014-09-12

Recent Filings

10 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
2017-10-19	CTMX	Other (J)	−6,000,000	$0	EDGAR
2017-10-11	RYTM	Conv (C)	+23,782,860	$0	EDGAR
2015-07-24	Larimar Therapeutics, Inc. (ZFGN) Delisted	Other (J)	−6,000,000	$0	EDGAR
2015-04-16	Foundation Medicine, Inc. (FMI) Delisted	Sell (S)	−12,296,334	-$614.82M	EDGAR
2015-03-25	Larimar Therapeutics, Inc. (ZFGN) Delisted	Other (J)	−7,000,000	$0	EDGAR
2015-02-19	AGIO	Other (J)	−9,210,270	$0	EDGAR
2014-09-12	bluebird bio, Inc. (BLUE) Delisted	Mixed	−3,605,760	-$13.70M	EDGAR
2014-01-17	bluebird bio, Inc. (BLUE) Delisted	Sell (S)	−921,000	-$20.65M	EDGAR
2013-10-02	Foundation Medicine, Inc. (FMI) Delisted	Conv (C)	+18,658,935	$0	EDGAR
2013-07-31	AGIO	Conv (C)	+15,056,880	$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.