Bank of America's headquarters in Charlotte, North Carolina. Image source: iStock/Thinkstock.

Shares of Bank of America (NYSE:BAC) are sharply lower on Friday after the U.S. Department of Labor said that job growth last month was the slowest it's been in more than five years. Halfway through the trading day, the bank's stock is down by 4%.

The issue for banks isn't necessarily what the estimate says about the economy, but rather what it suggests about the direction of interest rates, which are heavily influenced by the Federal Reserve's monetary policy.

Speculation has increased over the last few months that the Fed could soon increase short-term rates for the second time since the financial crisis. Much of this has been fueled by the central bank itself.

At the end of last month, Federal Reserve Chairwoman Janet Yellen said that an interest rate hike would "probably" be appropriate at some point in the near future if economic data improves.

The latest report, however, suggests that the economy is going in the opposite direction. Over the last year, the U.S. economy added an average of 220,000 non-farm payroll jobs a month on a seasonally adjusted basis. But last month the figure was only 38,000.

The jobs figure for May was the lowest it's been since September 2010. It also came in well below expectations. The Wall Street Journal, for instance, had predicted that payrolls would rise by 158,000.

Data source: U.S. Dept. of Labor.

Because higher interest rates act to suppress economic growth and thus job formation, it seems increasingly likely that the downbeat news will influence the Fed to hold off raising rates when it meets this month.

This is bad news for Bank of America because higher interest rates will translate into higher profits. It estimates that a mere 100 basis point simultaneous increase in short- and long-term rates -- that is, one percentage point -- will boost its net interest income by $6 billion a year.

It would be an understatement to say that Bank of America desperately needs this to happen. In the first quarter of the year, its return on assets, a keystone profitability figure in the bank industry that compares a bank's profits to its average total assets, was 0.5%. That's half the 1% rate that most banks strive for.

Suffice it to say that a $6 billion pre-tax boost to Bank of America's top line would go a long way toward bridging this gap -- which, in turn, would go a long way toward increasing the valuation of its stock. Bank of America's shares currently trade for a 40% discount to book value, whereas a bank that sustainably earns 1% or more on its assets will trade at or above book value.

As a Bank of America shareholder, I would certainly like to see this come to fruition. However, as has been the case for much of the last eight years, it looks like we'll just have to continue to be patient.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.