Ami Forte's affair with Roy Speer, co-founder of Home Shopping Network, could cost Morgan Stanley $400 million.

The affair began in 1998 and continued for around 12 years. Despite knowing about it, wife Lynnda Speer didn't divorce her husband. Now, the 75-year-old widow has filed a lawsuit against Morgan Stanley Wealth Management, 57-year-old financial adviser Ami Forte and branch manager Terry McCoy.

Morgan Stanley and Ami Forte allegedly engaged in 12,000 unauthorized trades and stole $40 million in fees, according to Inquistr.

Business Insider reported that Morgan Stanley would be paying for $400 million loss, including $100 million in compensatory damages, and an additional $300 million in punitive damages.

According to an earlier report in Yahoo!Finance: "Morgan Stanley believed it might be on the hook for a lot less - only $170 million. The reason the fine may end being bigger than expected is because of a state statue in Florida, the Florida Elder Exploitation Law."

Morgan Stanley denies the claims against it.