According to THR

The top-selling disc of the week was either Walt Disney Studios’ Wreck-It Ralph or Lionsgate’s The Twilight Saga: Breaking Dawn – Part 2.

It all depends on how you look at things.

Disney’s animated feature topped the Nielsen VideoScan First Alert chart, which tracks overall disc sales, its first week in stores. The film, which earned $187.9 million at the domestic box office, also debuted at No. 1 on Nielsen’s dedicated Blu-ray Disc sales chart for the week ending March 10.

But in terms of total unit sales, the crown goes to second-ranked Breaking Dawn because it was available in several different configurations that are listed separately on the First Alert chart – including a Wal-Mart-exclusive two-pack that also includes Breaking Dawn – Part 1.