Meyer, who arrived at Sirius XM the same year as Karmazin, in 2004, oversees the company's auto industry relationships, which account for the bulk of its revenue.
"At a company as complex as Sirius, with the satellites, media and automotive parts, gluing it all together is Jim," said a source who used to work at the company. "He is the No. 2 and worked with him closely."
A committee led by Greg Maffei, CEO of Sirius XM's majority shareholder, Liberty Media, is conducting a search to find Karmazin's successor and is examining both external and internal candidates. Maffei said on Liberty's Nov. 6 earnings call that the CEO search could take up to six months.
Karmazin, who was hired as CEO of Sirius Satellite Radio in 2004 and orchestrated its merger with XM Satellite Radio in 2008, will step down from his role in February. His decision dovetailed with Liberty's gaining a controlling interest in Sirius XM through a gradual increase in its ownership stake over the past year.