Citing a Major League Baseball source, the Miami Herald reported on Wednesday that the deal could be finalized in the next few days. Three-quarters of baseball's owners would need to approve the sale.
Neither team would comment.
The Expos are expected to be either contracted or taken over by Major League Baseball, which would buy the team from Loria in case contraction is aborted, leaving him an opportunity to own the Marlins.
Other teams wanting to acquire the star players in a dispersal draft likely would fight such a move.
Baseball commissioner Bud Selig already has said he wants to eliminate the Expos and Minnesota Twins before the start of next season. But the Players' Association has stated its opposition to such a move.
Henry is part of a group bidding for the Boston Red Sox. But he may be left out of baseball altogether in 2002 with Cablevision chairman Charles Dolan in the running to buy the Red Sox.