First National will follow PNC, Citizens and National City Bank of Pennsylvania as the region's largest banks, with assets totaling $6.9 billion and employing about 2,780, including 1,780 in Pennsylvania.

"This is a natural market extension for us," said First National chief executive officer Stephen Gurgovits, 58, who began his career 40 years ago as a First National teller.

The bank, based in Hermitage, will operate branches in Allegheny and Westmoreland counties, and executives also plan to scout for properties in the larger, more lucrative market of Pittsburgh.

First National currently runs 42 branches north of Pittsburgh and 12 in northeastern Ohio. Promistar, formerly known as BT Financial Corp., will vault First National into the region with 72 branches south and east of Pittsburgh.

First National's parent company, FNB Corp., also competes in southwestern Florida, where it has acquired eight banks.

"A lot of people were skeptical about it," Gurgovits said. "They thought we were just looking for an excuse to move to Florida."

The move began when First National's capital base grew during the 1990s, and executives saw that there weren't many lending opportunities in Pennsylvania. When an old friend and former executive, Gary Tice, founded a bank that lacked sufficient capital to keep up with Florida's high growth, the two decided to merge their institutions in 1997.

First National went on to purchase seven community banks and the Florida market accounted for roughly half of the bank corporation's assets before the Promistar deal.

"FNB has made tremendous progress in repositioning itself for higher growth through that acquisition program," said Peter Winter, an industry analyst for CIBC World Markets, New York.

Gurgovits said Wall Street may have doubted the bank's moves, "but I think those clouds are starting to clear."