Shares of Radian Group ( RDN) were among the NYSE's winners Wednesday, rising 8% after the mortgage insurance company posted better-than-expected fourth-quarter earnings.

The company earned $158.4 million, or $1.96 a share, on revenue of $347.9 million. Analysts polled by Thomson First Call expected earnings of $1.50 a share on revenue of $356.4 million. During the year-earlier period, the company earned $104.5 million, or $1.24 a share, on revenue of $298.6 million.

"Radian delivered record net income and grew book value by 16.1%, despite a challenging operating environment for our businesses including tight credit spreads and competition from alternative products," the company said. Shares were trading up $4.55 to $61.78.

Smurfit-Stone Container ( SSCC) jumped 8% after the paperboard company swung to a better-than-expected fourth-quarter profit. The company reported net income of $22 million, compared with a year-earlier loss of $92 million. Per-share earnings, which include stock dividends, totaled 9 cents. The results included a 2-cent restructuring charge and a 3-cent gain from foreign currency translation. Sales, meanwhile, rose to $1.82 billion from $1.65 billion. Wall Street expected earnings of 6 cents a share, before items, and sales of $1.77 billion.

Looking ahead, Smurfit-Stone said it expects "meaningful" year-over-year improvement in 2007 operating results, though first-quarter results will be down sequentially due to seasonal factors. Shares were trading at $11.03, up 79 cents.

Shares of Encore Acquisition ( EAC) rose 7% after Standard & Poor's said it will add the energy company to its S&P MidCap 400 index on a to-be-determined date. The company will replace McData ( MCDTA), which is being acquired by Brocade Communications ( BRCD). Shares of Encore were trading up $1.56 to $26.01.

Pactiv ( PTV) fell 7% after the packaging products company posted in-line fourth-quarter earnings and weaker-than-expected sales. The company earned $52 million, or 39 cents a share, on revenue of $738 million. Analysts expected earnings of 39 cents a share on revenue of $770.2 million. A year earlier, Pactiv recorded earnings from continuing operations of $35 million, or 25 cents a share, on revenue of $741 million.

Looking ahead, Pactiv sees first-quarter earnings of 37 cents to 41 cents a share, in line with analysts' average projection of 39 cents. Shares were trading down $2.35 to $33.23.

Shares of Norfolk Southern ( NSC) fell 3% after the railroad company posted fourth-quarter results that were below expectations. The company earned $385 million, or 95 cents a share, on revenue of $2.32 billion. Analysts expected earnings of 96 cents a share on revenue of $2.39 billion. A year earlier, Norfolk Southern earned $362 million, or 87 cents a share, on revenue of $2.26 billion. Shares were down $1.71 to $52.02.

Steel Dynamics ( STLD) fell modestly after the steel company posted mixed fourth-quarter results and gave a soft guidance for the first quarter. The company's fourth-quarter earnings rose to $105.1 million, or $1.03 a share, from $64.9 million, or 65 cents a share, a year earlier. Revenue rose to $839.8 million from $569.6 million. The earnings matched analysts' expectations, but revenue was below Wall Street's target of $894.1 million.

Looking ahead, Steel Dynamics forecast earnings of 85 cents to 90 cents a share. Analysts, meanwhile, project earnings of 97 cents a share. "Although the first quarter appears to be slightly softer than the fourth quarter due to continued weakness in the flat-rolled sector, it will still be stronger than the first quarter of 2005," the company said. Shares were trading at $34.84, down 7 cents.

NYSE volume leaders included Corning ( GLW), up $1.72 to $20.56; Advanced Micro Devices ( AMD), down $1.27 to $16.24; Ford ( F), down 5 cents to $8.25; EMC ( EMC), up 37 cents to $13.92; AT&T ( T), up $1.31 to $36.67; Nokia ( NOK), up 10 cents to $20.05; Pfizer ( PFE), up 19 cents to $26.56; and Texas Instruments ( TXN), up 53 cents to $30.13.

Nasdaq volume leaders included Sun Microsystems ( SUNW), up 38 cents to $6.04; Yahoo! ( YHOO), up $1.64 to $28.60; Cisco Systems ( CSCO), up 48 cents to $26.52; Intel ( INTC), up 21 cents to $20.76; Microsoft ( MSFT), up 35 cents to $31.09; Sirius Satellite Radio ( SIRI), down 1 cent to $3.77; Level 3 Communications ( LVLT), up 23 cents to $6.18; Applied Materials ( AMAT), up 6 cents to $17.52; and Apple ( AAPL), up 83 cents to $86.53.