Jack Dorsey has resigned has CEO of Twitter, leaving him free to concentrate on leading his other company, payments giant Square.
Dorsey has been CEO of both public companies since 2015, when he returned to Twitter, the social network he co-founded.
Last year, hedge fund Elliot Management, a major Twitter shareholder, sought to replace Dorsey on the grounds the firm should have a CEO solely focused on running the company.
The hedge fund later backed off but has now got its wish, with Dorsey making way for chief technology officer Parag Agrawal.
In an email to Twitter staff, posted by Dorsey, the outgoing boss stresses that "this was my decision and I own it".
Dorsey has made no comment on his role at Square, which he co-founded in 2009, but the payments firm may be a better vehicle for his cryptocurrency passion.