The one way that corporate income is falling

U.S. corporate debt continues to hit new all-time highs. The chart above shows how little operating income (technically, non-financial companies' funds from operations) supports the median American company's ever-growing debt load.

Think of this in personal finance terms. Financial advisers like to say that you shouldn't have total debts, including your mortgage, of more than 2.5 times your income. In corporate America, that ratio is now more than 6.5 times.

• Up until now, interest rates have been low and credit has been flowing freely, making it easy for companies to service these debts. But now rates are rising, and these debt loads could start to bite.

"Given where we are in the credit cycle, there are concerns about how and when prevailing conditions will turn. Such a change could spark bouts of strong volatility and periods of rapidly rising financing costs and illiquidity — limiting borrowers' financial flexibility — giving rise to increased defaults."