MGM has become the latest major film studio to offer downloadable movies on Apple's iTunes Store.

The Metro-Goldwyn-Mayer Studios Inc. deal, announced Wednesday, builds the catalog to more than 500 movies.

The studio is offering classic movies such as "Dances With Wolves," "Mad Max," and "Rocky," and will add other titles to iTunes in coming weeks, the two companies said.

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Apple's online store began offering movie downloads in September.

The Cupertino, Calif.-based company launched the feature initially with films from Walt Disney Co. studios, where Apple Inc.'s (AAPL) CEO Steve Jobs is the largest shareholder, but has since signed deals with other major studios, including Paramount Pictures and Lionsgate Entertainment Corp. (LGF)

Notably missing from iTunes are films from Sony Corp.'s (SNE) Sony Pictures, General Electric Corp.'s (GE) Universal Studios and Time Warner Inc.'s (TWX) Warner Bros., which have already started distributing movies on rival services from Wal-Mart Stores Inc. (WMT) and Amazon.com Inc. (AMZN)

Still, iTunes reigns as the world's most popular online movie store with more than 2 million movies sold, said Eddie Cue, Apple's vice president of iTunes.

"We'd love to have all the movie studios, that's certainly our goal," he said in a phone interview. "I think it's just a matter of time."

Cue likened the studios' pace of acceptance to those of TV show providers, some of which took a wait-and-see approach before signing up for a new method of digital distribution through Apple's online store.

"Some just want to see how the marketplace develops first," Cue said.

Issues, such as Apple's insistence for a simple pricing structure, must also be worked out during negotiations with the studios, he said.

Most movies on iTunes are $9.99 per download.