Chicago drew closer to a fiscal free fall on Friday with a rating downgrade from Moody’s Investors Service that could trigger the immediate termination of four interest-rate swap agreements, costing the city about $58 million and raising the prospect of more broken swaps contracts. The downgrade to Baa2, just two steps above junk, and a warning the rating could fall further still, means the third-biggest U.S. city could face even higher costs in the future if banks choose to terminate other interest-rate hedges against fluctuations in interest rates.