A Morgan Stanley wealth manager who had an affair with a client could cost the bank $400 million

A high-flying Morgan Stanley investment adviser, Ami Forte, has the bank facing an enormous fine, a source says.

The fine would be the result of a lawsuit filed against the bank by the widow of a multimillionaire client.

The widow is Lynnda Speer, who was married to Roy Speer, cofounder of the Home Shopping Network. He died in 2012. Now Lynnda Speer says the bank overcharged her husband while he was alive.