Town Chairman David Sheepshanks has thanked Marcus for his services to the Club and said on the club's official website: "It's always disappointing to part with a player of Marcus Stewart's ability.
"He has been a brilliant buy for this Club, and has done incredibly well over the two and a half years that he has been with us. On behalf of the Club, I'd like to thank Marcus for his tremendous efforts.
"It's always very sad to see a popular player leave and I understand supporters' frustration at seeing favourites depart. However, I can only reiterate that we would not have agreed to this sale, or others previously, unless they were necessary for the future well being of the Club.
"The need to work within financial limits is no sign of lack of ambition, as we are utterly determined to regain our Premiership status.
"Player sales are simply a consequence of relegation and the cold fact that we cannot afford a squad of the same size as last season in Division One. Furthermore, you cannot sell those who no club wants to buy.
We have a fine squad of players despite Marcus' departure with five other strikers competing for the first-team. We have to look forward not backwards."