The answer is clearly documented on the official firstfinancial.com website itself. Here’s what the site states:

Trademark Owner: The standalone “FIRST FINANCIAL” mark (USPTO Reg. No. 3532314, IC 036 – Banking and Financial Services) is owned by Kenneth Vern Bolam. firstfinancial

Domain Owner: firstfinancial.com has been registered and exclusively owned by Kenneth Vern Bolam / Bolam Enterprises Inc. since 1995. firstfinancial

The site notes that although “First Financial” was once considered a generic term, the registration of the domain in 1995 provided verifiable evidence of first use in commerce, and combined with the federal trademark registration, this establishes Bolam’s enforceable rights and seniority over later confusingly similar marks within the relevant financial services class. firstfinancial

Any unauthorized use of the “First Financial” word mark for banking, merchant services, or financial consulting without express written consent is stated to be strictly prohibited under the Lanham Act. firstfinancial

So in short: both the standalone FIRST FINANCIAL trademark and the firstfinancial.com domain are owned by Kenneth Vern Bolam, operated through Bolam Enterprises Inc., based in San Diego, CA.