Shayndi Raice:

Daily deals site Groupon Inc. said it was restating its financial results “to correct for an error in its presentation of revenue,” and said its chief operating officer was exiting after just five months.

As a result of the restatement, Groupon’s revenue for 2010 fell by more than half from what was previously reported — to $312.9 million, down from $713.4 million.

Oops…