Bank investors have suffered two lost decades

After an awful start to 2016, the S&P 500 bank index (Exchange:.5SP401010) is at the same level as in the fall of 1996.

Not that it hasn't been a rocky road: The banks doubled over the next 10 years, then crashed amid the financial crisis, before running right back to where they started. And bank investors did enjoy dividends over the years.

But especially compared to an S&P 500 (^GSPC) that is up some 170 percent in the same time period, the abject lack of price performance is striking.

"What investors need to understand is that even over the long term, a sector cannot do well," Eddy Elfenbein of the "Crossing Wall Street" blog commented in a Friday interview on CNBC's " Trading Nation ."

Those who bought the banks back then have proven especially unlucky, however. Even the hammered energy sector has nearly doubled over the past two decades.

Some particular names have fared even worse. Bank of America (BAC) shares, for instance, are down 42 percent since October 1996. Citi (NYSE:C) shares have fallen 65 percent in that time.

Recent concerns for bank investors have included exposure to energy loans, as well as interest rates that may continue to be low for the foreseeable future, pressuring margins. But more generally, the big banks haven't gotten back the mojo they lost in the financial crisis.

If there's a bright spot, says Elfenbein, it's that "valuations are really cheap" at present.

Small consolation, that, for those who haven't seen their stocks rise in the time since America was doing the "Macarena."

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