Former Twitter CEO Dick Costolo joins Index Ventures as partner, cofounds new fitness startup
Six months after stepping down as CEO of Twitter, Dick Costolo has revealed what his next move will be, now that he's handed control of the social network back to Jack Dorsey.
Context & Ripple Effects
Costolo's exit from Twitter unfolded in stages through 2015: the June handoff to Jack Dorsey as interim CEO, a stated plan to leave the Twitter board by year-end or when a permanent CEO was named, and a side stint consulting two days a week in the HBO Silicon Valley writers' room. This announcement closes that arc with a split next act — a seat at Index Ventures plus a founder role in fitness.
First-order effects
- Index Ventures gains a consumer-internet operator who ran Twitter through its scale-up years, adding operating judgment to its partnership at the deal-sourcing level.
- Costolo's fitness startup begins life with a cofounder whose public profile and network date to running a top social platform — distribution leverage most first-time founders lack.
Second-order effects
- Founders pitching Index's consumer and social deals now face a partner who has sat in the CEO chair during a high-pressure transition, raising the bar for go-to-market scrutiny.
- The dual partner-plus-founder arrangement puts Index in the position other firms have faced when a partner's outside commitment competes for attention — governance questions about time allocation come with the hire.
Third-order effects
- The pattern of ex-CEOs stacking a venture role on top of an operating project — rather than choosing one next act — points toward senior operators treating VC seats as portfolio careers, which reshapes how firms weigh partner capacity against brand value.
- For Twitter specifically, the full departure of its prior leadership under Dorsey marks the completion of a generational reset in which the returning founder controls both product and narrative.
The trend: Post-CEO careers are fragmenting into simultaneous venture-capital and founder roles, with operators converting their networks into equity positions rather than taking a single successor job.