FNB Corp. bucked a trend in the financial industry by reporting that its earnings rose a strong 33.5 percent in the third quarter.

The Hermitage-based holding company said Thursday it earned $23.5 million, or 27 cents a diluted share, in the third quarter, compared to $17.6 million, or 29 cents a diluted share, in the same year-ago period.

Recent third-quarter results were boosted in part by the company completing the purchase of Iron and Glass Bancorp Inc., which bolstered its presence in Pittsburgh.

The deal added a $167 million loan portfolio, $254 million in deposits and total assets of $310 million as of Aug. 16.

A number of financial institutions have been posting huge losses in recent months as many of them bet large sums in the subprime lending market which has been drowning in bad loans. FNB has continually said it was not a player in the subprime market.

“We are pleased to deliver a solid quarter in this period of economic stress,’’ said Bob New, FNB’s president and chief executive officer. “Our results reflect the successful balancing of our growth initiatives with our strong risk management practice. The strong organic growth we experienced in loans, deposits and treasury management balances demonstrates that we continue to win in the marketplace. We have benefited from a flight to quality given the disruption in the banking industry and amongst some key competitors in our markets.’’

In the company’s third quarter, return on average tangible equity was 25.7 percent, its return on average equity was 10 percent, return on average tangible assets was 1.28 percent and its return on average assets was 1.13 percent.

New added that the company was proud to reach record levels of assets at $8.5 billion and shareholders’ equity at $1.0 billion.

“All-in-all I would say this is a very decent earnings report,’’ said David DeForest, a stock broker with Butler Wick & Co.’s Sharon office. “They hit shareholder equity of $1 billion and that’s pretty impressive. It shows strength.’’

FNB is a diversified financial services company and is a leading provider of commercial and retail banking, leasing, wealth management, insurance, merchant banking and consumer finance services in Pennsylvania and Ohio. The company is best known locally for its First National Bank of Pennsylvania affiliate, which is also based in Hermitage. FNB also operates consumer finance offices in Tennessee and loan production offices in Pennsylvania, Ohio, Tennessee and Florida.

FNB announced its earnings after the stock market closed. FNB’s stock closed Thursday at 11.37, down 46 cents or 3.89 percent.