LinkedIn Corp. finished last year with a solid fourth quarter, but the online professional networking service rattled investors with a forecast indicating that growth is cooling more than estimated. LinkedIn also said it is buying Bright, a startup that specializes in making data analysis tools to connect job hunters with employers. In the quarter, LinkedIn earned $3.8 million, or 3 cents per share, down from a year earlier. Revenue climbed 47 percent to $447 million, beating estimates. For the first three months of this year, however, management predicted revenue of up to $460 million, below an estimate of $471 million.