Stock index futures fell sharply on Tuesday, with the S&P 500 set to enter a bear market as European officials considered making banks take bigger losses on Greek debt and fears of contagion grew.

S&P 500 futures fell 13 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures sank 122 points, and Nasdaq 100 futures lost 21.5 points.