Facebook (FB -13.2%) tumbles in early trading to $33.20; even after the selloff, the company trades at nearly 23x sales and 75x trailing EPS. Not helping is BTIG's decision to launch coverage at Neutral; in-line with earlier comments, the firm is worried about Facebook's valuation, decelerating growth, and ad monetization issues. Also lower: RENN -8.3%. ZNGA -7.1%. YELP -6.8%. LNKD -6.1%. GRPN -4.8%. SVVC -7.4%. GSVC -10%.