Including its record-breaking midnight screenings early Wednesday, Harry Potter and the Half-Blood Prince earned a monumental $58.4 million on its first day in U.S. theaters. Not so monumental that Michael Bay will be firing off any angry letters about a threat to Transformers 2's own best-ever opening day, but still. Forecasters predict a $150-million-plus take by the end of business on Sunday; call your shots in the comments, and check back with Moveline Attractions tomorrow morning for our own peerless weekend projections. [Variety]