A financier was a person that managed large amounts of money for investing or lending.
Mr. Brack, an alias assumed by the immortal Flint around 2239, was a wealthy financier. (TOS: "Requiem for Methuselah")
Ralph Offenhouse, a Human rescued by the USS Enterprise-D in 2364, was a financier on Earth in the 20th century. (TNG: "The Neutral Zone")