LinkedIn Corp. lnkd shares dropped in the extended session Thursday after the social network's outlook fell well below Wall Street estimates. LinkedIn shares plummeted 22% to $149.73 on heavy volume. The company said it expects adjusted earnings of 55 cents a share in the first quarter on revenue of $820 million, and $3.05 to $3.20 a share for the year on revenue of $3.6 billion to $3.65 billion. Analysts surveyed by FactSet had estimated 75 cents a share on revenue of $868.3 million for the first quarter, and $3.70 a share on revenue of $3.91 billion for the year. For the fourth quarter, LinkedIn reported adjusted earnings of 94 cents a share on revenue of $861.9 million, while analysts were forecasting 78 cents a share on revenue of $857.3 million.