Just to clarify: earnings are not revenues. Earnings are revenues - costs. Facebook and Twitter's valuations are both infinitely times their earnings since ne

Just to clarify: earnings are not revenues. Earnings are revenues - costs. Facebook and Twitter's valuations are both infinitely times their earnings since neither has any earnings right now. However, their negative earnings are still important (especially on a per-user basis). So, Facebook's P/E ratio is non-existent since they have no earnings.