United Parcel Service Inc.'s (UPS) second-quarter income fell 49% on continued weak demand, with the shipping bellwether warning that conditions have yet to improve substantially and forecasting disappointing third-quarter results.

The most optimistic view that UPS executives offered is that business trends appear to be stabilizing.

Chief Financial Officer Kurt Kuehn said the broad economy isn't getting "dramatically worse," but he noted that UPS remains "cautious" on its outlook because few signs of an imminent rebound are evident.

UPS shares were trading recently at $51.20, off 2.1%.

The company projected third-quarter earnings of 45 cents to 55 cents per share, below Wall Street's consensus forecast of 59 cents per share, according to Thomson Reuters.

It said it expects average daily domestic package volumes to be down about 4.6% in the third quarter, equal to the second quarter slide. Average daily international export volumes likely will be down 4% to 6%, after falling 7.3% in the second quarter, the company said.

The earnings warning is the latest for UPS, which like virtually every industry linked to freight has seen steep declines in volume.

Earlier Thursday, German shipping company Deutsche Post AG (DPW.XE) reported that its volumes "may have seen the bottom," but it also said it doesn't expect world trade to make a substantial recovery in coming months. FedEx Corp. (FDX) warned last week it was bracing for soft demand into next year.

Kuehn told analysts on a post-earnings conference call Thursday that "stagnant economic activity around the world negatively impacted all of our business segments" in the second quarter, and he said the company is bracing for more of the same until it sees clear indications of improvement.

As a diversified transportation company that moves everything from documents to building materials, UPS, along with rival FedEx, is considered a barometer for the state of the U.S. economy.

UPS posted second-quarter income of $445 million, or 44 cents a share, down from $873 million, or 85 cents a share, a year earlier. The latest quarter included 5 cents in currency and other charges. In April, the company projected earnings of 45 cents to 55 cents per share, below analysts' estimates at the time.

Revenue decreased 17% to $10.83 billion. Analysts most recently expected $11.02 billion.

Operating margin fell to 8.3% from 11.2%, while average revenue per package fell 11%.

U.S. package revenue fell 12% as the unit's profits slid 47%. In the international packages division, revenue dropped 24% and profits declined 29%.

-By Bob Sechler, Dow Jones Newswires; 512-394-0285; bob.sechler@dowjones.com

(Kerry Grace Benn contributed to this report)