Josh Flagg of Rodeo Realty was the listing agent. Donovan Healey of John Aaroe Group repped the buyer.
The sale marks the second time the property has changed hands in the past year. Last May, it sold for $8.25 million. Marx, who died in 2011 at 89, sold the home six years ago for $1.685 million, records show.
The house is also nearby the onetime Art Linkletter estate, which Katz acquired last year for $34.5 million in an off-market deal. He is currently developing the 4.6-acre estate, according to real estate sources.
Katz, 54, is a Canadian investor and businessman who bought the NHL franchise in 2009. Last year, he partnered with Hollywood producer Joel Silver to form the production company Silver Pictures Entertainment.
His net worth is estimated at $3.2 billion, according to Forbes.