Sunderland will not spend their way out of trouble in the January transfer window, says chief executive Martin Bain.
The Black Cats are bottom of the Premier League, two points from safety after three wins in 15 games.
Bain described Sunderland's level of debt as "not healthy" and said manager David Moyes would not make big-money signings next month.
"We have very limited transfer funds available for January," he added.
Bain highlighted Sunderland's high turnover of players in recent seasons as one of the reasons for the club's "difficult financial backdrop".
He said they had made a profit on just three of the 46 players they have sold since 2009.