The 64-year-old signed on in April to reprise his role of Gordon Gekko in Oliver Stone-directed Wall Street sequel Money Never Sleeps.
Douglas told Empire that the new movie "predominantly focuses on these last couple of years on Wall Street".
He said: "It's 22 years later. Gordon has done about eight years in jail and got out in about 2001. The picture predominantly focuses on these last couple of years on Wall Street, which nobody anticipated.
"We shot the first one in 1986 and it was a wild, wild colourful time. And here we have both a train crash and a larger-than-life period leading up to that train crash. It's an exciting time to make a picture about Wall Street."
He added: "We've got Josh Brolin playing what I guess is the villain of the piece. There's a little bit of Terence Stamp, from the first one, in there. Allan Loeb wrote a good script and when Oliver signed on he put his fingerprints all over it.
"I think it'll be a relevant movie. It's all to do with the execution, I guess."
It was previously reported that Charlie Sheen will make a cameo appearance as his Bud Fox character from the original film.