Shares of Owens Corning plunged Wednesday after the company reported adjusted second-quarter earnings below Wall Street's expectations. It also reaffirmed a 2010 earnings prediction that misses analysts' estimates.

Shares fell $2.89, or 9.2 percent, to $28.66 in afternoon trading.

The Toledo, Ohio, company's second-quarter earnings, boosted significantly by a tax gain, were $937 million, or $7.33 per share, compared with year-ago earnings of $33 million, or 26 cents per share. Adjusted to exclude one-time items, including the $844 million tax gain, earnings were $73 million, or 57 cents per adjusted share, compared with $62 million, or 49 cents per share in the second quarter of 2009.

Revenue rose to $1.38 billion from $1.22 billion a year earlier.

The company attributed the higher results to increased global demand in its composites business, an improving performance in its building materials segment and narrowed losses in its insulation segment despite continued weakness in the U.S. housing market.

But analysts were looking for more. Those surveyed by Thomson Reuters, who generally exclude one-time items, expected a profit of 60 cents per share on revenue of $1.38 billion.

Also Wednesday, the company reaffirmed its adjusted earnings it 2010 earnings forecast of about $2 per share. Analysts currently expect $2.07.