Re/code: Twitter has been engaged in an ongoing series of talks to acquire Flipboard, according to multiple sources with knowledge of the situation, in an all-stock deal that would value the company at over $1 billion. Those discussions have been taking place since the beginning of the year, said sources, as the social communications giant has faced increasing pressure from Wall Street to grow its audience and innovate its products. But despite a flurry of activity more recently, sources said these talks seem to be currently stalled.