Twitter tumbled at the opening bell on Wednesday a day after the microblogging site reported weaker-than-anticipated growth in users, even as it posted a surge in revenue. Twitter was down more than 12% to $37.27, hitting a new low. Twitter reported average monthly active users of 255 million, slightly below analysts' consensus estimates. "User growth serves as canary once more," Evercore analyst Ken Sena told clients in a note. "This quarter represents at least Twitter's 4th in a row of stepped user growth deceleration, suggesting to us that some users are beginning to find alternative elsewhere."