The city is entangled in a total of 24 swap contracts whose value fluctuates with short-term interest rates. Under those contracts, the current combined liability for the city — the total the city might have to pay if its debt rating dropped to "junk" status today — is nearly $400 million. That would only happen in the event of a downgrade on both the city's taxpayer-backed debt and the somewhat better-rated debt from its airport, water and sewer programs.