NEW YORK – PNC Financial Services Group Inc. said Monday it is buying the U.S. subsidiary of Spain’s BBVA bank for $11.6 billion in cash. BBVA's U.S. operations, which are based in Houston, Texas, have $104 billion in assets and operate 637 branches, mainly in the south and southwest of the country. “Our acquisition of BBVA USA will accelerate our growth trajectory and drive long-term shareholder," said William Demchak, PNC's president, chairman and CEO. Regional banks face stiffer competition now from big national banks and have been hurt more than larger banks by low interest rates. The president of BBVA, Carlos Torres Vila, said the price of the deal was high, at about 2 1/2 times the level analysts had valued the U.S. unit.