Pep Boys’ shares were up 6.3 percent in extended trading on Monday, in line with Icahn’s latest bid of $18.50 per share, which values the U.S. auto parts retailer at about $1 billion. Icahn had earlier offered $16.50 per share and said he would top any fresh offer from Bridgestone by 10 cents, capping it at $18.10. In response to Icahn’s bid, Bridgestone on Dec. 24 raised its offer by $1.50 to $17 per share.