Zillow (Z +8.6%) finished sharply higher thanks to its Q4 beat and solid guidance, and so did Trulia (TRLA +5.2%). Citi (Buy) is pleased with the 90% Y/Y growth seen in Premier Agent revenue (65% of total), and also likes a 47% Y/Y increase in monthly unique users to 34.5M. But the firm is a little worried about Zillow's aggressive spending. On the earnings call, management noted mobile made up over half of January visits, and now accounts for 1/4 of Mortgages revenue. Zillow and Trulia are respectively up 17% and 28% since Tuesday's close thanks to their Q4 reports.