After leaving Twitter, Costolo got into the fitness-tech space for personal reasons. He's a runner and Crossfit addict, and saw an opportunity to engage others in sports. But he had a few other ideas to explain the interest of so many fellow Twitter alums in health-tech.
"At Twitter, we were always mission-centric," he said.
So it seemed logical to Costolo that his former colleagues would be attracted to companies with a strong mission.
"In Silicon Valley, we joke that every company thinks they're changing the world," he said. "But with health, you can see an immediate impact rather than needing to jump through verbal hoops to convince yourself."
The other factor is the network effects. Just like the PayPal mafia, a group of high-profile former employees that chose to invest in each other, the Twitter alumni in health care are picking up the best and brightest from their former workplace.
Twitter's former media chief Katie Jacobs Stanton served on the board of Color Genomics alongside fellow Twitter colleagues Elad Gil and Othman Laraki before making the decision to join full-time. She subsequently snapped up Linda Jiang and Jeff Dejelo, both from Twitter.
"Yes I do think there's a network now," she said. "But we also recognize that the (health) space is wide open and there's so much opportunity."
Baljeet Singh, who now works at a diabetes management start-up called Livongo Health, said he was shaped by the "rough patches" at Twitter. At times of intense scrutiny, he recalled that the all-hands meetings reminded him of the company's mission. "It bound us together and got people fired up," he said.
"I didn't want to join a start-up that was doing things your parents used to do for you, like food delivery or laundry services," Singh said. "I thought that tech could play a much bigger, and more socially impactful role in the world than that."
Here's a list of all the former Twitter execs we know of who have gone into health care or biotech. (The first title on each line is their former position at Twitter. None of them work there now.)
- CEO Dick Costolo, who's now running a fitness app called Chorus Fitness
- Data science leader Jesse Bridgewater, who's now running the data science team at Livongo Health
- Media heads Katie Jacobs Stanton, who now runs marketing at a personal genetics company Color, and Ross Hoffman, now Headspace's chief business officer
- Vice presidents Elad Gil and Othman Laraki, who co-founded Color Genomics
- Senior product director Baljeet Singh who's now at chronic disease management start-up Livongo Health
- Vice president of engineering Nandini Ramani, now chief engineer at Outcome Health
- Industry manager Julie Martin, who's now working with Costolo as head of partnerships at Chorus Fitness; and ex-Twitter senior product manager Erin Moore, now head of product at Chorus Fitness
- Principal engineer Marius Eriksen, who is now a software engineer at cancer-detection start-up Grail
- Data scientist Charles Gorintin, who is now co-founder of a digital insurance company called Alan
- Software engineering manager Dmitriy Ryaboy, now a vice president of software engineering at computational biology company Zymergen
- Vice president of sales finance Jeff Dejelo, now running finance at Color
- Strategy and operations manager Linda Jiang, now consumer marketing at Color
- Mobile market manager Charles Wu, now director of product at Catalia Health
- Director of global operations Rita Garg, who left the company for a senior business development role at Zenefits
- Intern Ray Bradford, now the CEO of Spruce Health
- Account executive Rick Cerf, now a product manager at Grand Rounds Health
- Recruitment manager Mel Heydari, now director of talent at Proteus Digital Health
- Revenue engineer Ashutosh Singhal, now at Benchling
- Software engineer Timothy Gushue, now at Driver
- Product manager Meekal Bajaj, now a product manager at Benchling
- Senior staff software engineer Brian Guarraci, now CTO at Cricket Health
- Leslie Carr, network engineer at Twitter, now infrastructure engineering manager at Clover Health
Correction: An earlier version of this story misspelled Othman Laraki's first name. This story has been updated to reflect new names that came to our attention after initial publication.