Shares of Yandex fell sharply early Tuesday after Russia's largest search engine logged disappointing fourth-quarter results. Yandex (YNDX) reported Q4 net income of $89 million, below analyst estimates. Sales were $290.4 million, in line with views. The company's shares tumbled 9.5% in mid-morning trading Tuesday. Yandex also said its revenue growth this year might slow to a range of 28% to 32% this year from 44% in 2012. "The market has matured,