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

The ministers signed off on a 30 billion euro ($40 billion) rescue package for debt-plagued 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.

As the market looks to grab something fresh with respect to the robust aid package, more strings are apparently attached to the deal, said Andre Bakhos, director of market analytics at Lek Securities in New York.

S&P 500 futures were up 0.2 points and were 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 gained 6 points, and Nasdaq 100 futures shed 0.5 points.

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

With earnings season breaking the ice, investors are hoping that the prior quarter's momentum will carry the market forward, added Bakhos.

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 16 percent to $12.45 and RRI Energy gained 14.2 percent to $4.51 in premarket trade.

Palm jumped 8.4 percent to $5.54 after Bloomberg News reported the company will seek bids as it tries to sell itself as early as this week, citing sources.

Heavy equipment maker Caterpillar Inc edged up 1.4 percent to $66.20 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.

European shares ticked up Monday after the agreement on Greece.

U.S. stocks rose Friday, with the Dow briefly surpassing 11,000 for the first time in a year and a half after Chevron Corp's upbeat outlook and wholesale inventories data reinforced bets on an improving economy.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)