Stock index futures rose on Monday on hopes policymakers were putting together new measures to help ease Europe's debt crisis, though the lack of clarity on their effectiveness was expected to keep markets volatile.

A move by European leaders to strengthen the European Financial Stability Facility bailout fund as well as reports of a possible repurchase of covered bonds by the European Central Bank lifted investor sentiment.

European shares rose 2.6 percent as the developments were seen as a stronger commitment from European leaders to avoid a Greek default.

A slightly better-than-expected reading on a German sentiment survey also lifted equities and the euro, though the data came in at its lowest level since June 2010, the month after Greece became the first euro zone country to receive a bailout.

We're going to be volatile until we see some consensus in Europe, said Jack de Gan, chief investment officer at Harbor Advisory Corp in Portsmouth, New Hampshire.

We can be plus or minus sharply any day, he said.

S&P 500 futures rose 17.5 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration of the contract. Dow Jones industrial average futures gained 153 points, and Nasdaq 100 futures added 29.25 points.

(Reporting by Rodrigo Campos; editing by Jeffrey Benkoe)