Standard & Poor's last night said it may upgrade Huntsman after the US chemicals company ended discussions over a sale which would have added to its $4.5bn (€3.8bn) of debt.

Huntsman confirmed late last year that it had received interest regarding an acquisition, and hired Merrill Lynch and SG Cowen as financial advisers and Vinson & Elkins and Weil, Gotshal & Manges as legal advisers.