A rare 1962 Ferrari 250 GTO sold for $48.4 million at RM Sotheby's annual collector car sale in Monterey, California. The sale set a world record for any car ever sold at auction. It beat out a Ferrari 250 GTO Berlinetta that sold for $38 million in 2014. Not close behind was a 1957 Ferrari that sold for $35 million in Paris, France, in 2016.

Considered "the Holy Grail in collectible cars," the 1962 Ferrari 250 GTO was sold by former Microsoft executive Greg Whitten. CNBC's Robert Frank spoke to Whitten on why he's selling the car before the auction took place on August 25.