LONDON — Fitch Ratings has found a way for banks to safeguard themselves from heavy losses should the commercial property market crash. Naturally, the greater percentage a bank lends towards a property, the greater risk the bank takes on. When it comes to commercial property — anything from offices to shops — in a major market downturn, it can be doubly risky because commercial real estate (CRE) owners can run up millions upon millions in debt, and if a business goes bust, it will not be able to pay its bills.