Cowen on Thursday downgraded Twitter to the equivalent of a sell rating, advising clients to avoid the stock after the social media platform reported weak revenue and lowered its guidance.

“We are moving to an underperform rating (from market perform) and a $12 target price (from $15) given sharply lower near-term forecasts, rising competitive pressures and strategic uncertainty amid a product transition,” equity analyst John Blackledge wrote in a research note.

Twitter shares plunged more than 12 percent Thursday in reaction to what Cowen analysts call “worrisome” advertising revenue and earnings trends ahead.