Twitter's Jack Dorsey cuts back on executive chairman role

SAN FRANCISCO, Oct 9 (Reuters) - Twitter founder andExecutive Chairman Jack Dorsey said on Tuesday that he trimmedhis role at the microblogging service months ago as he devotedthe majority of his time to Square, the payment start-up wherehe is chief executive.

Dorsey transferred all of his employee supervision toTwitter Chief Executive Dick Costolo in January as part of apre-arranged transition process, Dorsey disclosed on his Tumblrblog.

"We haven't talked about this publicly because it's not whatpeople using Twitter every day care about," Dorsey wrote.

Dorsey took to his personal blog to clarify his role atTwitter, the messaging service he invented in 2006, after TheNew York Times reported he had taken on a diminished role at thecompany after employees complained that he was "difficult towork with."

Dorsey was previously Twitter's CEO until 2008, when he waspushed out by Twitter co-founder Evan Williams. He launchedSquare that year.

Dorsey returned to his current role at Twitter in March2011. He caused a stir within Silicon Valley last November whenhe said at a conference that he worked 8 hours at each company-- totaling 16 hours every day -- by being "very disciplined."

(Reporting By Gerry Shih; Editing by Tim Dobbyn)

((Gerry.Shih@thomsonreuters.com)(+1 415 515 1698))