U.S. stock index futures were modestly higher on Monday, the first session after hitting a 19-month high, as investors awaited key earnings reports and a Greek official said an aid package would help avert a sovereign debt default.

Still, some uncertainty over the aid package pushed up the nation's borrowing costs to a 12-year high one day after Greece's finance minister said the assistance would avert a default. The situation in Greece has weighed on equities in recent weeks.

Earnings season continues in full swing, with Caterpillar Inc set to report. The Dow component's results could provide insight into how the manufacturing sector is faring in the recovery. Texas Instruments Inc , BlackRock Inc and Boston Scientific Corp are also due.

Both Whirlpool Corp and Humana Inc posted adjusted earnings that beat expectations, and Whirlpool also raised its full-year profit view.

S&P 500 futures rose 2.5 points and 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 gained 21 points while Nasdaq 100 futures added 1.75 points.

UAL Corp's United Airlines and Continental Airlines Inc disagree over the price of a potential stock-for-stock merger, according to sources.

Also on the merger front, Hertz Global Holdings Inc agreed to buy rival car rental company Dollar Thrifty Automotive Group Inc for about $1.2 billion, while Charles River Laboratories International , the U.S. clinical research company, plans to acquire WuXi PharmaTech Cayman Inc for $1.6 billion.

The two Democratic Senators trying to come up with a bill regulating the $450 trillion private swaps market are near a deal, and will include a provision to require banks to spin off swaps desks, sources said Sunday.

European stocks were up 1 percent Monday morning, led by banking shares, as worries eased over Greece's woes <.EU>. while Japan's Nikkei average <.N225> jumped 2.3 percent.

U.S. stocks hit a 19-month high Friday as Merck rose after it said costs from healthcare reform will be lower than its rivals.

(Editing by Jeffrey Benkoe)

Japan Caterpillar