Yahoo’s back – but that’s not a good thing for Yahoo.

Following its rosiest quarter since Marissa Mayer took over as CEO in July 2012, the portal saw its overall revenue sink in the fourth quarter after improving year-over-year in the third quarter for the first time under Ms. Mayer.

Yahoo’s overall revenue fell 1% to $1.3 billion in the fourth quarter, the company reported on Tuesday. The figure fell short of analysts’ estimates. The company turned a $166 million profit but that number was twice as big a year ago.

Yahoo’s mobile revenue was seemingly a lot bigger than a year ago when the company wouldn’t break out how much money it makes from smaller-screen devices. Yahoo made $254 million in mobile revenue during the fourth quarter. That figure doesn’t include the revenue that Yahoo shared with third parties. When including that shared money, Yahoo’s gross mobile revenue totaled $413 million for the quarter and $1.26 billion for the year to beat Ms. Mayer’s previous projection of $1.2 billion.