Los Angeles-based PacWest Bancorp and Westlake Village-based First California Financial Group have received the go-ahead from federal banking regulators to finalize a $237 million merger. The deal, which will merge First California into PacWest and likely result in about a dozen overlapping branches being shuttered, is expected to close on May 31.

The banks said they received the final regulatory approval on May 10. Shareholders of both banks had already given the deal their blessing in March.

First California reported last week that its first-quarter earnings dropped from $2.4 million to $391,000. The bank, currently the largest based in the Tri-Counties with assets of about $2 billion, said in regulatory filings that the decline in profitability ahead of the merger with PacWest was as a result of lower net interest revenues from lower yields on interest-earning assets, higher Federal Deposit Insurance Corp. shared-loss asset amortization, and higher legal, audit and other professional expenses related to the deal.