Why one of the biggest concerns about Facebook's business could be overblown

Morgan Stanley analyst Brian Nowak thinks that concerns about Snapchat's threat to Facebook are overblown.
"We don't believe Snapchat is having a material impact on FB's engagement or daily active user (DAU) growth," he wrote in a note to investors on Monday.
Nowak said he's seen a fear of Snapchat eating away at the attention of Facebook's younger audience reflected both in conversations and in the company's stock price.
Andrew Left at Citron Research, for example, has categorized Snapchat as