Bournemouth will be taken over by a Las Vegas-led group by the end of October.
The owner of the Las Vegas Golden Knights is thought to be leading the bid.
There is a period of exclusiveity over the purchase of the club with terms and a price already agreed.
Bournemouth were promoted from the second tier.
The club is owned by a man who was born in Russia.
The new owners hope to be in place at the stadium by the end of the month.
The group led by Todd Boehly took over the club in May.
Some of the UK's biggest companies have US investment.
Gary O'Neil said at the news conference that he had not been informed of any change in ownership of the club.
He didn't hear anything over his side.
We are working on the football side to make sure we are prepared. I have not heard anything about a takeover.
Simon Stone is a sports reporter for the British Broadcasting Corporation.
The owners of the San Francisco 49ers have a minority stake in the City Football Group, but they are not included in the total number of United States owned clubs in the English top flight.
The 77-year-old American is the owner of the Golden Knights and, according to him, there is money to be made.
Fans will want more information about the funding of the sale if current owner Demin agrees to it, particularly if it involves the type of borrowing that was used to complete the purchase of the club.
Supporters of too many clubs have been stung by apparent new ownership offering hope of a bright future only for the reality to be somewhat different.