(Reuters) - Snap Inc missed Wall Street estimates for fourth quarter revenue on Tuesday, hurt by a shorter holiday season, sending its shares down 12%.Snap, which owns the popular photo messaging app Snapchat, had earlier warned its peak advertising demand period, which runs between the Black Friday and December holidays, had one fewer week.Revenue, which the company generates from selling advertising on Snapchat, rose 44% to $560.88 million, but missed the average analyst estimate of $563.03..