Leeds United have slumped into the red after the absence of European Champions League football this season took its toll.
The company revealed an interim pre-tax loss of £13.8m (€22.3m), compared with a previous profit of £100,000 (€162,000).
The club was also hit by expensive player purchases, such as the £11m (€18m) signing of Robbie Fowler.
Turnover dipped to £38.3m (€62m) from £41m (€66m).
The company will not pay a dividend.