There has been speculation the Hammers will have to sell players in January because of the financial crisis in Iceland that has affected owner Bjorgolfur Gudmundsson - although the club's manager Gianfranco Zola has repeatedly insisted that is not the case.
England defender Upson said: "Speculation can be flattering and is part of what's happening at the club. There are rumours every player is for sale but the owners haven't clarified anything. It's a difficult period financially and people are aware but I'm happy playing here at the moment, I am enjoying my football."
The Hammers are one place above the Premier League relegation zone and also face a potential £30million payout to Sheffield United over the Carlos Tevez affair.