undamentalytics Newsletter

Dexcom insider trading

Every open-market purchase and sale by Dexcom's officers, directors and largest shareholders since November 4, 2021, and what the share price did next.

Insider purchase Insider sale Marker size reflects trade value. Weekly closes adjusted for splits; may be delayed.
Dexcom insider open-market trades
DateInsiderTrade SharesPriceValue 1M after 3M after 6M after

From insiders' Form 4 filings with the SEC: open-market purchases and sales only (awards, option exercises and shares withheld for tax are excluded), combined to one line per insider per day. "Plan" marks trades the filing says were made under a pre-set Rule 10b5-1 trading plan, which are scheduled in advance. Price changes run from the close on the trade date; hover a figure for the change relative to the S&P 500. Past moves don't predict future ones.

Does following Dexcom’s insiders pay?

From March 17, 2010 to November 10, 2025, 35 insiders reported 13 open-market purchases and 248 sales not made under a pre-set plan in Dexcom. Twelve months after each purchase was reported, the shares were +56.2% against the S&P 500 on average (median +33.9%), over 12 purchases with a full year of prices; 83% beat the index. After sales, the shares moved +20.3% against the index over 12 months (a negative figure means selling was the right call). That rests on fewer than 20 purchases, too few to read much into. Buying each purchase the day after it was reported, an equal amount each, held 12 months or until that insider reported a sale, would have turned $10,000 on May 13, 2010 into $210,701 by November 2, 2026, +20.4% a year. It held shares 34% of the time; the S&P 500 on those same days, with Treasury bills otherwise, made $27,485 (+6.3% a year), and held throughout $87,248 (+14.1%).

$0$100k$200k 201020122014201620182020202220242026 $211k$87.2k$27.5k
Copying Dexcom's insidersS&P 500, same days investedS&P 500, held throughout $10,000 copying every open-market purchase by Dexcom's insiders from May 13, 2010, before costs and taxes, marked weekly. Uninvested money earns the Treasury bill rate; the portfolio held shares 34% of the time.
Dexcom: each insider's record
InsiderRolePurchases12 months after their purchasesBeat the S&P 500Sales12 months after their salesLatest report
Gregg Terrance H Executive Chairman 1 +24.1% (1) 100% 50 +13.4% (50) April 24, 2017
Leach Jacob Steven President & COO 1 — — 17 −1.6% (17) November 10, 2025
Doubleday Richard EVP Chief Commercial Officer 0 — — 16 +51.1% (16) January 6, 2021
Sayer Kevin R Chairman, CEO & President 0 — — 16 +14.2% (16) March 14, 2025
Balo Andrew K * 0 — — 14 +49.3% (14) March 12, 2021
Pacelli Steven Robert Managing Dir., Dexcom Ventures 0 — — 14 +42.1% (14) September 13, 2021
Moy Jeffrey EVP Operations 0 — — 13 +48.0% (13) March 13, 2020
Sylvain Jereme M EVP, Chief Financal Officer 0 — — 12 −16.6% (12) March 14, 2025
Valdes Jorge A CTO 1 +19.5% (1) 100% 10 +36.7% (10) August 9, 2016
Kahn Barbara Director 0 — — 10 +26.8% (10) November 20, 2017
Lord Jonathan T Md Director 2 +20.5% (2) 100% 7 +15.8% (7) September 6, 2016
Skyler Jay S Director 2 +100.7% (2) 100% 7 −13.9% (7) May 16, 2018
Abbey Donald EVP Quality and Regulatory Aff 0 — — 7 +52.9% (7) September 13, 2021
Stern Sadie EVP, Chief HR Officer 0 — — 7 −32.9% (7) March 14, 2025
Altman Steven R Director 2 +179.5% (2) 100% 4 −2.4% (4) September 16, 2020
Murphy Patrick Michael EVP, Chief Legal Officer 0 — — 6 +35.1% (6) September 13, 2021
Roper Jess SVP, CFO 0 — — 6 +43.7% (6) November 16, 2015
Blackford Quentin S. Chief Operating Officer & CFO 0 — — 4 +54.8% (4) March 12, 2021
Augustinos Nicholas Director 0 — — 3 +34.2% (3) August 8, 2018
Doordan Martin Director 3 +24.6% (3) 67% 0 — March 12, 2012
Foletta Mark G Director 0 — — 3 +31.8% (3) August 28, 2018
Lister John General Counsel, VP of HR 0 — — 3 +78.6% (3) November 15, 2013
Topol Eric Director 0 — — 3 +39.5% (3) June 13, 2018
Ace Heather S SVP Human Resources 0 — — 2 +2.2% (2) March 13, 2020
Brown Michael Jon EVP, Chief Legal Officer 0 — — 2 −39.6% (2) March 14, 2025
Dolan Matthew Vincent EVP, Strategy & Corporate Dev 0 — — 2 −44.8% (2) January 30, 2025
Selvaraj Shelly Ramasamy SVP Information Technology 0 — — 2 −17.7% (2) May 28, 2020
Shrishrimal Sumi SVP Chief Risk Officer 0 — — 2 −22.6% (2) September 13, 2021
Collins Richard Alexander Director 0 — — 1 −8.2% (1) November 29, 2021
Gerhardsson Peter VP, Int'l Bus. Dev. 1 −43.9% (1) 0% 0 — November 18, 2010
Lawver Teri L EVP Chief Commercial Officer 0 — — 1 −56.1% (1) March 14, 2024
Lucas Donald L Director 0 — — 1 +25.3% (1) March 17, 2010
Naganathan Girish EVP Chief Technology Officer 0 — — 1 −63.8% (1) November 27, 2023
Patterson Chad EVP, Global Marketing 0 — — 1 −23.3% (1) September 13, 2021
Regan Barry J. EVP Operations 0 — — 1 −12.2% (1) November 23, 2021

Moves are the shares’ return including dividends minus the S&P 500’s, from the close on the first trading day after each report; the number of trades with a finished 12-month window is in brackets. Green means the trade went the insider’s way (a purchase ahead of the index, a sale followed by the shares trailing it). A trade reported both by a director or officer and by a fund or company they are linked to counts once here, under the person. Purchases count only where the share price actually traded was at least $5. These figures describe what the shares did, not why anyone traded. Insiders across all companies.

When several insiders traded Dexcom

Months when 2 or more insiders became net buyers, or 3 or more net sellers, of Dexcom in reports dated in the 91 days before the month end, and how the stock did against the S&P 500 from that month end. After the 2 buying crowds with six months of prices, it averaged +16.9% against the index. After 14 selling crowds, +13.6%. One company's history is too short to judge by; the test across every company is the better guide.

MonthCrowd3 months on, vs S&P 5006 months12 months
January 31, 20245 selling−0.2%−55.2%−53.6%
September 30, 20218 selling−12.4%−12.4%−25.6%
March 31, 20219 selling+10.5%+41.5%+27.2%
September 30, 20208 selling−23.5%−31.9%+2.7%
March 31, 202011 selling+30.4%+19.3%−22.8%
September 30, 20198 selling+36.1%+92.6%+155.3%
March 29, 20198 selling+21.6%+19.1%+138.9%
May 31, 20183 selling+53.6%+39.5%+34.2%
November 30, 20173 selling−7.9%+55.3%+115.9%
March 31, 20173 selling−16.7%−49.9%−24.6%
May 31, 20163 selling+37.5%+3.5%−13.8%
August 29, 20148 selling+12.7%+27.3%+112.6%

Colours show whether the crowd was right: green when buyers were followed by a rise above the index, or sellers by a fall below it. Latest 12 of 16. Total returns from the month end; past patterns are not a forecast.

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