Bank Earnings Start as Lower Rate Impact Debated

Falling U.S. interest rates are good news if you're financing a car, buying a home, or expanding your business. But falling rates are sweet and sour for the major U.S. banks preparing to report third-quarter earnings later this week, and already have raised concerns about bottom-line impact.

When rates fall, worries can mount about banks' ability to continue generating the net-interest income (NII) that's driven so much profit over the last two years. The largest banks open their books starting Friday less than a month after the first Federal Reserve rate cut in more than four years. The Fed's "jumbo" 50-basis-point rate trim on September 18 precedes what the Fed and market participants expect to be a series of further trimming later this year and next.

As a reminder, NII measures the money banks make lending minus what they pay to customers. Banks store money, so higher rates help them make more money just as they help bank customers looking to sock money away. When rates go down, banks make less when they purchase bonds or lend money.

The Nasdaq Bank Index (BANK) chopped around this autumn, losing ground from its late July peak and not recovering fully even after the Fed's rate cut. The financials sector's uncertain trajectory coincided with a drop in the 10-year Treasury note (TNX) yield, which traded below 4% through August and September after spending most of the second quarter between 4.2% and 4.7%.