Twitter founder Jack Dorsey said Monday he'd step down as CEO after a series of missteps — including the censoring of a bombshell story on Hunter Biden — and a share price that stubbornly lagged behind peers. The long-bearded and nose-ringed Dorsey, who had been under pressure from hard-charging billionaire Paul Singer's hedge fund Elliott Management after doing double duty as CEO of Twitter and payments giant Square, said a hand-picked successor, Parag Agrawal, would succeed him.