United Parcel Service Inc., the world's largest package delivery company, posted a higher-than-expected quarterly profit and raised its full-year outlook on expectations of modest growth in the holiday season.

Third-quarter net income rose to $991 million, or 99 cents per share, from $549 million, or 55 cents a share, a year earlier.

Excluding special items, profit was 93 cents per share, beating analysts' forecasts for 88 cents, according to Thomson Reuters I/B/E/S.

BB&T Capital Markets analyst Kevin Sterling attributed the earnings beat to growth in the company's international air freight and cost controls.

UPS said it expected full-year earnings per share to rise more than 50 percent to a range of $3.48 to $3.54, excluding special items. It had previously forecast $3.35 to $3.45, and Wall Street had expected $3.45.

"Every day they move about 7 percent of U.S. GDP," Sterling said, "so if they say they expect modest holiday season growth, they probably know better than anyone else."

Revenue rose 9.3 percent to $12.19 billion, short of the analysts' estimate of $12.4 billion.

The Atlanta company's shares were up 0.5 percent at $69.97 in premarket trading.

At Wednesday's close, UPS shares were up 19.8 percent year to date, while smaller rival FedEx Corp had gained 4.4 percent.

UPS and FedEx are considered indicators of U.S. economic activity as their business expands or shrinks with the broader economy.