Twitter shares gained Tuesday on word that co-founder Biz Stone was returning to the social network after six years away.

Stone said in an online post that he will be back at work full time at the San Francisco-based operation in “a couple of weeks,” prompting shares to end the New York Stock Exchange trading day up 1.35 per cent to $19.49 (£15.09).

“Excited to have Biz’s energy and heart back at Twitter,” co-founder and chief executive Jack Dorsey said in a tweet fired off from his @Jack account with a hashtag #Biz

Stone left Twitter in mid-2011 during executive shake-ups and joined co-founder Ev Williams in forming a startup called Medium.

Stone said in his post that he sold his most recent enterprise and was recently visiting Twitter’s headquarters when, at an employee gathering, Dorsey asked him to return.

“There’s something about the personality of a company that comes from the folks who start it,” Stone said.

“Jack coming back was a big step forward. And now, it’s my turn.”

Stone expected his focus to be on guiding company culture.

“You might even say the job description includes being Biz Stone,” he quipped.