Traders work on the floor of the New York Stock Exchange on Dec. 28, 2015.

Check out the companies making headlines after the bell Monday:

Pep Boys stock soared in extended-hours trading. This move came on the heels of activist investor Carl Icahn's increased bid against competing tire company Bridgestone to acquire Pep Boys. Icahn is the second-largest shareholder with more than 11 percent of the auto parts company.