Four San Diego banks announced plans to merge.

A merger between First National Corp. and three other San Diego banks will create San Diego County’s second-largest independent bank with $418 million in assets and nine branches. Describing it as the first “merger of equals” in the West, First National, parent of First National Bank, has signed an agreement in principle to merge with National Bankshares of La Jolla, National Bank of Fairbanks Ranch and Rancho Santa Fe National Bank of Fairbanks Ranch through an exchange of common stock.