Rackable Systems ( RACK) saw its shares plunge Wednesday, a day after the company said earnings for the fourth quarter would soundly miss Wall Street's targets. The Milpitas, Calif., company said revenue for the quarter ended Dec. 30 is expected to be in the range of $105.5 million to $106.8 million, in line with analysts at Thomson First Call who pegged sales at $106.1 million for the fourth quarter. However, earnings, excluding items, are forecast in the range of $4.8 million to $5.3 million, or 17 cents to 18 cents a share, widely missing the consensus forecast of 27 cents a share. Rackable's shares recently plummeted 31.4% to $22.25. Rackable, which competes with Dell ( DELL), Hewlett-Packard ( HPQ) and Sun Microsystems ( SUNW), sells servers and storage products used by large Internet companies. The company will report its earnings on Feb. 1.