PayPal Inc. helped drive its parent eBay Inc. to its first profit increase in more than a year.

In the fourth quarter, volume in eBay's payments business, which includes PayPal and BillMeLater, rose 34%, to $21.4 billion. Payments revenue rose 28%, to $795.6 million.

The parent company said it expects PayPal's sales to reach $5 billion by 2011, making the unit its biggest moneymaker.

"We still have a lot of work to do," John Donahoe, eBay's chief executive, said in an interview. "This is not declaring victory. This is simply saying we've reached another milestone in what we said we'd do."