With the growing profits from Hunt Foods, he began buying stock in other undervalued companies with growth potential, many of which were still undervalued following the loss of confidence in equities after the Great Depression. He diversified through acquisition into well known businesses such as McCall's Publishing, the Saturday Review of Literature, Canada Dry Corporation, Max Factor cosmetics, the television production company Talent Associates, and Avis Car Rental, through his holding company Norton Simon Inc. (Norton Simon Inc. was formed in 1968 through the merger of Hunt Foods, McCalls Publishing and Canada Dry Corporation.) Many of these businesses had extensive interests outside the United States. Norton Simon Inc. was later acquired by Esmark in 1983, which merged with Beatrice Foods the next year. Beatrice was sold to ConAgra in 1990.
The Italian and other governments are becoming far more aggressive in seeking the repatriation of looted antiquities. Italy in particular waged a long legal battle against Getty curator of antiquities, Marion True, for acquiring illicitly exported pieces, although the case finally exhausted the statute of limitations. And in recent years numerous American museums – including the Metropolitan Museum of Art in New York, Boston’s Museum of Fine Art and the Getty in Los Angeles – have been forced to return looted antiquities to their host countries. These include the famed Etruscan Euphronios krater (wine bowl) dating from 515 BC and which was bought by the Met in 1972 for $1.2m. It turned out that this had also been handled by Medici, and the museum gave it back to Italy in 2006. Just this month, the Getty said it was returning a 12th-century Byzantine illuminated New Testament to the Greek Dionysiou monastery – from which it had disappeared more than 50 years ago.
Simon accumulated a significant private art collection which included works of the Impressionists, Old Masters, modern and native art. In the 1960s, he spent $6 million on artworks – an inventory of slightly less than 800 objects – and real estate – a building at 18 East 79th Street – from the Duveen Gallery in Manhattan, which specialized in old masters. Scholars including the critic Clement Greenberg and the Metropolitan Museum of Art curator Theodore Rousseau studied the Duveen purchases for Simon and were able to identify numerous misattributions. Simon ended up selling much of the collection and only kept around 130 objects, primarily paintings, a handful of sculptures, a few porcelains, and a cape purportedly worn by Charles IV of Spain. However, his collection holds three autographed Rembrandt paintings, considered highly important works of Rembrandt in Southern California.
In August 2004, experts examined the works and found inconsistencies. Greene, who had shipped the works from his home in San Francisco, had also been unable to provide provenance and import and export documentation. The collection committee proceeded to veto the annuity deal made months prior. That same year, the de Young museum pulled out of a deal with Greene, this time in exchange for Philippine tribal art, for similar reasons.