Oh, how the mighty have fallen. Just months after sat radio powerhouses Sirius and XM merged, the singular entity is teetering on collapse. The company (and formerly, companies) have always been pretty strapped for cash, but it appears that its leverage has almost expired. According to a recent report from the Associated Press, it’s expected that the satellite radio company could file for bankruptcy as early as Tuesday.Apparently, the firm is having a difficult time negotiating with the holders of its debt,