Stocks trended downward after the bell Monday, but the health care sector served up a few winners.

Among these was PDL BioPharma ( PDLI), which jumped 6.6% in heavy trading on word the Redwood City, Calif. company has put itself up for sale. The decision arose from an ongoing evaluation of strategic alternatives, said PDL.

In addition, Chief Executive Mark McDade has resigned. Board chairman L. Patrick Gage will replace him in the interim, and Karen Dawes will fill in for Gage. Shares gained $1.41 to $22.78.

M&A news also fired up ViaCell ( VIAC), which rocketed 48.4% to come in as one of the biggest late price gainers. The biotech company, based in Cambridge, Mass., agreed to sell itself to PerkinElmer ( PKI) for $7.25 a share in cash, or around $300 million. The deal should close in the fourth quarter.

ViaCell surged $2.31 to $7.08, as PerkinElmer ticked up 4 cents at $29.90.

Fellow health care stock AngioDynamics ( ANGO), a diagnostic-device maker, posted a fiscal first-quarter profit of $2.4 million, or a dime a share. That's in line with Thomson Financial's estimates. A year ago the Queensbury, N.Y. company made $1.9 million, or 12 cents a share. AngioDynamics also reaffirmed its fiscal 2008 outlook. Shares climbed 4.2% to $20.65.

But Palm ( PALM), which makes smartphones and other handheld devices, ranked among the after-hours losers on a soft fiscal second-quarter outlook . The Sunnyvale, Calif., company expects to see a non-GAAP profit of 6 cents to 8 cents a share, or least 3 cents below the Street's consensus. First-quarter earnings topped by a penny, but shares were still sliding 70 cents, or 4.4%, to $15.30.

Online media-and-advertising firm Miva ( MIVA) slipped as well, after the company pegged third-quarter sales at between $36.7 million to $37.1 million. That's below its earlier range and under the mean $38.4 million target. Shares of the Florida-based company were down substantially after the close, before pulling up to a penny loss at $4.63.