Shares of Mentor Graphics ( MENT) plunged 14.8% to $5.18 after the company warned on Tuesday that it would post a loss for the third quarter on lower-than-expected revenue. For the quarter ended in October, the developer of software tools for the design of semiconductors said it will lose 5 cents a share, excluding charges, on revenue of $185 million. Analysts polled by Thomson Reuters were expecting earnings of 15 cents a share, excluding charges, on revenue of $215.1 million. The company also lowered its guidance for the fourth quarter. It now expects revenue of $270 million and earnings, excluding charges, of 55 cents. Analysts were looking for revenue of $318.6 million and an adjusted profit of 93 cents a share. Shares of Virgin Mobile ( VM) were up 9.4% to $1.05 after handily topping Wall Street expectations for its third-quarter profit. The company earned $4.07 million, or 7 cents a share, in the quarter ended Sept. 30, compared with a loss of $7.38 million, or 29 cents a share, a year ago. Excluding one-time items, Virgin Mobile earned 8 cents a share, well above analysts' expectations of 4 cents a share, according to Thomson Reuters.