Complex sentence: The bank was housed in a converted saloon directly across the street from the Columbus Savings & Loan as an institution for the "little fellow" coining the phrase "the small guy", a new bank for the hardworking immigrants other banks would not serve.
Split into simpler sentences: The bank was housed in a converted saloon directly across the street from the Columbus Savings & Loan as an institution for the "little fellow". It was a new bank for the hardworking immigrants other banks would not serve.