Director Oliver Stone was shocked when he revisited the world of high finance for the sequel to his 1987 hit movie Wall Street, describing what was happening there as the collapse of capitalism.

Why did I go back?...Because it's important. It's the collapse of capitalism and the collapse of our society. It is. Our way of life is going to change, Stone told Vanity Fair magazine in an interview.

I was truly, truly shocked when I went back (to Wall Street), the Oscar-winning director told the magazine in an interview for its April edition.

A million dollars had become a billion dollars. They'd replaced people of substance with people who made money. The Volckers had become the Greenspans, he said.

But Stone said his first aim, as always, was to tell an entertaining story. And to tell a story of financial manipulation on Wall Street is one of the hardest things you can do.

Wall Street: Money Never Sleeps, which features the return of Michael Douglas as disgraced insider trader Gordon Gekko, opens in the United States on April 23.

Gekko, just out of jail, wants back in the game in a tale set at a time when the global economy is teetering on the brink of disaster.

Transformers star Shia LaBeouf, 23, plays the role of an analyst of alternative energy companies at two Wall Street firms -- one modeled on investment bank Goldman Sachs and the other on its collapsed rival Bear Stearns.

Stone said his late father, who worked for a brokerage firm, had encouraged him years ago to work on Wall St.

But I wasn't any good at mathematics, Stone said, adding, I tried hard to understand Enron. I read three books. I couldn't understand a...thing.

(Reporting by Jill Serjeant; Editing by Bob Tourtellotte)