In recent months, Treasury borrowings costs have declined, because investors around the world engaged in a flight to safety.
However, it was only reached by ignoring the interest payments on Greece's borrowings, the cost of recapitalising its banks, and other one-off measures.
The fees are labeled as points -- a term used in most borrowings to describe loan costs beyond the interest rate -- with each point representing 1percentt of the principal.
That doesn't hurt lending profits if a bank can also reduce the cost of its borrowings.
If rates rose even a tenth of a percentage point, the added cost on those borrowings would be $405 million a year.
Moody's more sober view, and any future rating cut, would increase the cost of future borrowings for the stadium.
As with all arbitrage, however, there is a risky side: "If interest rates spike, the cost of your borrowings will quickly outpace the rate of return you're getting on your policy," Mr. Troth said.
The guarantee could mean ratings agencies would classify the airline as a government-related entity, allowing it to regain an investment-grade credit rating and reducing the cost of its borrowings.
United are the Premier League's richest club by far, their income a record £331m in 2010-11, byosted by huge figures for matchday and broadcasting revenue; but their financial power is hampered by their owners, whose borrowings, now down to £308m net, cost the club £51.7m in interest last year.
But the accounts also provide a figure for the contractual maturity of its financial liabilities, which includes the interest costs relating to those borrowings.
