Variety reports that THE DARK KNIGHT sold 600,000 Blu-ray discs on Tuesday alone – more than the previous record-holder, IRON MAN, sold in a week. However, home video sales remain in a slump. DARK KNIGHT’s total sales of both Blu-ray discs and DVDs was 3 million on its first day, up to 4.4-million by Wednesday. Those numbers sound – indeed, are – impressive, until you realize that HARRY POTTER AND THE GOBLET OF FIRE sold 5 million copies on its first day of release in 2006, and FINDING NEMO (the record holder) sold 8 million way back in 2003. Industry insiders are happy that DARK KNIGHT is doing as well as it is, but the continued decline in DVD sales, down about 6% from last year, has everyone hoping that converting viewers to Blu-ray will re-ignite the slumping home video business.