U.S. stock index futures pointed to a flat open on Monday as euro zone finance ministers approved a massive emergency aid plan for debt-stricken Greece, easing sovereign debt concerns.

The ministers signed off on a 30 billion euro ($40 billion) rescue package for Greece on Sunday, but stressed that Athens had not yet asked that the plan to be activated.

Separately, a German government spokesman raised a potential hitch by saying European leaders would have to agree at a special summit to activate the aid mechanism.

I'm a little bit surprised as we are heading into earnings season that these sort of stories are having what appears to be a pretty strong effect, said Peter Jankovskis, co-chief investment officer at OakBrook Investments LLC in Lisle, Illinois.

Once trading starts here the focus will be back on earnings.

S&P 500 futures were off 1.3 points but were slightly above 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 lost 10 points, and Nasdaq 100 futures shed 1 point.

Earnings season gets underway after the close of trading, with Alcoa Inc , the aluminum major and Dow component, due to report results.

UBS AG delivered its highest pretax profit since the credit crisis began and said withdrawals had slowed substantially.

Mirant Corp led a new batch of mergers and acquisition activity after the company agreed to take over rival RRI Energy Inc , while Palm Inc
is reportedly looking to sell itself.

Mirant agreed to buy RRI Energy to potentially create one of the largest U.S. independent power producers and cut costs as the industry copes with weak electricity prices. Mirant shares surged 13.2 percent to $12.15 and RRI Energy gained 12.4 percent to $4.44 in premarket trade.

Palm jumped 8.7 percent to $5.61 after Bloomberg News reported the company will seek bids as it tries to sell itself as early as this week, citing sources.

California Pizza Kitchen Inc advanced 4.2 percent to $21.60 after the restaurant operator confirmed it is exploring a possible sale and raised its earnings outlook for the first quarter.

Heavy equipment maker Caterpillar Inc edged up 1.4 percent to $66.15 after Baird raised its rating on the stock to outperform from neutral as part of a larger call on the diversified industrial and machinery sector.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)