DreamWorks Animation SKG Inc agreed to buy privately held Classic Media for $155 million, adding characters such as "Casper," "Richie Rich" and "Lassie" to its franchise business.

DreamWorks, the studio behind the "Shrek" franchise and this summer's "Madagascar 3: Europe's Most Wanted," will pay cash for the rights-holding company, owned by Boomerang Media Holdings I LLC, a portfolio company of private-equity firm GTCR LLC.

Classic Media and Jay Ward Productions -- a television cartoon producer founded by American animator Jay Ward -- jointly manage the rights to Ward's catalog, which also includes "Rocky & Bullwinkle" and "Mr. Peabody & Sherman".

DreamWorks Animation's 3D feature film Mr. Peabody & Sherman is scheduled for release in December 2013.

New York City-based Classic Media, which has about 80 employees, owns 450 film titles and more than 6,100 episodes of animated and live-action programming, DreamWorks said.

"Classic Media brings a large and diverse collection of characters and branded assets that is extremely complementary to DreamWorks Animation's franchise business," DreamWorks' CEO Jeffrey Katzenberg said.

"We plan to leverage it across our motion picture, television, home entertainment, consumer products, digital, theme park and live entertainment channels."

Classic Media reported net revenue of $82.2 million and an operating profit of $19.2 million for the 12 months ended Feb. 29.

DreamWorks will finance the deal through a combination of cash and credit, and said it expects it to add to earnings in the first full year after the acquisition is completed.

JPMorgan Chase & Co advised DreamWorks on the transaction and Jefferies & Co was adviser to Classic Media.