Investment giant JP Morgan is seeking to snap up a slice of Twitter, insiders tell the Wall Street Journal. The firm's new $1.2 billion Digital Growth Fund is in talks to acquire a minority stake in the microblogging site in a deal that would value Twitter at around $4.5 billion, say the sources, who stress that talks are ongoing and no deal has been struck yet. The fund—which is targeting private Internet and digital-media companies—is also looking for a stake in online gaming heavyweight Zynga and coupon provider LivingSocial, the sources say. (More JPMorgan Chase stories.)