Updated from 10:02 a.m. EDT

B2B outfit

Ariba

(ARBA)

reported a narrower fourth-quarter loss on Wednesday, but its revenue fell from a year ago. The company provided first-quarter guidance in line with Wall Street estimates.

Using generally accepted accounting principles, Ariba reported a loss of $142.5 million, or 54 cents a share, compared with a loss of $224.3 million, or 89 cents a share, in the year-ago period. Revenue fell to $58.2 million from $62.6 million a year ago, amid a weak tech spending environment.

On the news, shares of Ariba were lately trading down 38 cents, or 16.7%, at $2.05.

Pro forma earnings were $5 million, or 2 cents a share, vs. a loss of $27.7 million, or 11 cents a share, a year ago. On that basis, Ariba beat estimates of a penny a share, according to Thomson Financial/First Call.

Ariba's pro forma earnings exclude certain noncash and special charges. They also keep out expenses of amortization of goodwill and other intangible assets, as well as stock-based compensation.

Ariba CFO Jim Frankola said Ariba expects first-quarter revenue to be flat to slightly up sequentially and pro forma earnings to be in the range of about 1 cents to 2 cents a share.

Wall Street analysts had projected first-quarter earnings of a penny a share on revenue of $58.8 million.

Frankola noted in an interview after the company's earnings were released that like other software companies, Ariba suffered a significant drop in revenue from 2001 to 2002 -- of about $180 million. But due to a restructuring, the company's pro forma income increased by $90 million over the same period.

The once high-flying business-to-business software maker has launched new spending management products that help companies not only create an auction to buy products and services but also structure the entire procurement transaction.

Staff writer Ronna Abramson contributed to this report