Standard & Poor’s recently released a proprietary cash flow modeling system for residential MBS. SPIRE, Standard & Poor’s Interest Rate Evaluator, gives users access to the same tools that S&P analysts use to obtain rapid feedback on potential securitization structures for RMBS. The modeling system can compute if the available funds derived each month from a loan or pool of loans, given S&P’s rating criteria, are sufficient to satisfy a capital structure’s bond liabilities. SPIRE