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Thomas DesRosier

CIK 1435744 · See Remarks · last filed 2026-08-18

Thomas DesRosier is a corporate insider who has filed 46 SEC Form 4 insider transactions across 5 companies since 2008. The most recent filing, for MCRB, was dated Aug 18, 2026. Across all open-market trades the lifetime net is −$1.0M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $481.9K across reported positions. 13 SEC filings were submitted jointly with CUBIST PHARMACEUTICALS INC.

"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

$481.9K

Companies

5

Total Filings

46

Lifetime Open-Market Net

-$1.03M

Filer Profile

Reported Address
65 HAYDEN AVENUE
LEXINGTON, MA 02421
Related Filers
CUBIST PHARMACEUTICALS INC — 13 joint filings, latest 2015-01-21
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
MCRB See Remarks 8,117 $5.01 $40.7K -$92.8K 26 2026-08-18
ARIAD PHARMACEUTICALS INC (ARIA) Delisted EVP, General Counsel 55,000 — — $0 3 2016-03-30
CUBIST PHARMACEUTICALS INC (CBST.Z) Delisted EVP, Chief Legal 0 — — $0 7 2015-01-21
CUBIST PHARMACEUTICALS INC (CBST) Delisted SVP, Chief Legal Officer & GC 191 — — $0 3 2013-10-02
GENZ Sr VP, General Counsel 11,571 $38.13 $441.3K -$937.1K 7 2011-04-06

Recent Filings

46 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
2026-08-18 MCRB Mixed +163 -$373 EDGAR
2026-07-10 MCRB Grant (A) — $0 EDGAR
2026-05-19 MCRB Mixed +165 -$595 EDGAR
2026-03-06 MCRB Grant (A) — $0 EDGAR
2026-02-18 MCRB Mixed +166 -$661 EDGAR
2025-11-18 MCRB Mixed +168 -$1.3K EDGAR
2025-08-19 MCRB Mixed +168 -$1.3K EDGAR
2025-05-19 MCRB Mixed +165 -$575 EDGAR
2025-02-19 MCRB Mixed +7,264 -$3.5K EDGAR
2025-02-11 MCRB Grant (A) — $0 EDGAR
Showing 1–10 of 46
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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.