Canaccord analyst Michael Graham said his analysis of listener hours in October and November appear to show Pandora's growth slowed noticeably. Slowing listener growth has been a concern for investors and the rates were well below historical averages, said Graham, who does not think December will be much better. Since the company already preannounced revenue and EBITDA exceeded the high end of guidance, the lower listener hours must be offset by better than expected ad RPMs and growth in subscription listening hours, concludes Graham, who maintained his Buy rating and $18 price target on Pandora shares.