First Security Corp., the Salt Lake-based bank holding company, plans to float up to $150 million in senior debt securities and subordinated debt securities periodically, according to a Securities and Exchange Commission filing.

On Dec. 15, First Security completed its purchase of the deposit liabilities of Pacific First Bank in Utah, and has applied for regulatory approval to buy the assets and assume the deposit liabilities of the Ogden, Utah, offices of MountainWest Financial.