Weak Debute for "Tron:Legacy" and "How Do You Know"

 (Reuters) - "Tron: Legacy," a costly 3D sci-fi movie that Walt Disney Co has promoted for more than three years, took the top spot at the North American box office, but with a disappointing weekend haul of $43.6 million, according to estimates issued by the company on Sunday.
The other big new release, "How Do You Know," a comedy featuring a high-priced lineup headed by Jack Nicholson and Reese Witherspoon, was a major flop. It earned $7.6 million, falling short of modest expectations. The ranking was not immediately available. The film was released by Columbia Pictures, a unit of Sony Corp.