Key TakeawaysSpotify added more subscribers than analysts expected in the third quarter.The audio streaming giant's subscriber outlook also came in slightly ahead of projections. Shares surged in extended trading Tuesday and have more than doubled in value since the start of the year. Spotify (SPOT) added more subscribers than expected in the third quarter, sending shares higher after the bell Tuesday. Monthly active users climbed 11% year-over-year to 640 million, and premium subscriptions came in at 252 ...