Bank holding company PacWest Bancorp (PACW) has reached a definitive agreement and plan of merger to acquire CapitalSource, in a cash and equity deal valued at nearly $2.3bn, to boost its footprint in southern California.

Post acquisition and subsequent integration, the united company will be branded as PacWest Bancorp and their combined subsidiary banks will be called Pacific Western Bank.

Operating as a division of Pacific Western Bank, the CapitalSource national lending operation will remain doing business under the same brand name, as per terms of the agreement.

PacWest Bancorp CEO and Pacific Western Bank chairman and CEO Matt Wagner will assume the post of CEO at the united organization and of Pacific Western Bank. CapitalSource CEO James Pieczynski will become president of the new CapitalSource division of Pacific Western Bank.

PacWest Bancorp chairman John Eggemeyer will become chairman of the combined company, whereas Tad Lowrey, chairman and CEO of CapitalSource Bank will be designated as non-executive chairman of Pacific Western Bank.

Already approved by the independent directors of both companies, the transaction is expected to complete during the first quarter of 2014 and is still subject to customary closing conditions as well as concerned regulatory approvals.

As at 30 June 2013, CapitalSource operates 21 branches located in southern and central California, with about $8.7bn in assets.

Pacific Western Bank, a subsidiary of PacWest Bancorp, had $6.7bn in assets at 30 June 2013 and 75 bank offices located throughout 10 California counties.

On a pro forma consolidated basis, as of 30 June 2013, the integrated institution would have almost $15.4bn in assets with 96 branches throughout California.

JP Morgan Securities, Wachtell, Lipton, Rosen & Katz served as advisors to CapitalSource, while Jefferies, Sullivan & Cromwell, Castle Creek Financial and Goldman Sachs & Co offered advices to PacWest.