PNC Financial Services Group estimated it will receive a tax benefit worth up to $725 million for buying troubled National City Corp., substantially less than some prior media estimates of $5 billion.

The estimate, the first time PNC has put a dollar figure on the potential windfall, was contained in a regulatory filing PNC made this morning.

PNC also said it may seek to raise additional capital in a public stock offering, but not at this time because of the poor economy and volatile markets.

PNC announced last month it would buy Cleveland-based National City in a stock transaction now valued at around $5.2 billion. PNC received $7.7 billion in federal bailout money to help buy National City, money it is to pay back at a 5 percent interest rate for the first five years.

Although PNC has said National City was seeking a buyer to avoid going bankrupt, the deal has come under harsh criticism from Ohio legislators who believe National City should have received aid from the bailout fund to stand on its own.

The merger is expected to close Dec. 31, but PNC has said it would take about 23 months to integrate National City's operations.