Complex sentence: During the Principate, most banking activities were conducted by private individuals, not by such large banking firms as exist today; since almost all moneylenders in the Empire were private individuals anybody that had any additional capital and wished to lend it out could easily do so.
Split into simpler sentences: During the Principate, most banking activities were conducted by private individuals, not by such large banking firms as exist today. Since almost all moneylenders in the Empire were private individuals, anybody that had any additional capital and wished to lend it out could easily do so.