Last Friday I went short on 200 shares of Randgold Resources Ltd as I felt they will fall soon. The bid price was 66.85 and the ask price was 66.90. I was astonished when the transaction went through (virtual trader) that the sell price for the short was executed at 22.50, instantly devaluing my stock by £10,000. Why was the short sold at that price? Thanks for any answers.