If there is no spike of sales, all hours of sales is worth the same, and assuming Amazon makes 100B per year in online sales, then it seems like a considerable loss, but still a drop in the bucket when compared to their total revenue:
(1 - (365 * 24 - 4) / (365 * 24)) = 0.000456621...
0.000456621... * 100,000,000,000 = $45,662,100.4566...