Bank valuations are also back up. Looking at price-to-book multiples, the most popular measure for valuing the sector, U.S. banks of the KBW banks index are trading near fair value at a 16% premium to book value, or about the same valuations in the summer of 2008. The sector has shown it is capable of trading a even higher valuations of three or even five times book value, but banks are unlikely to return to the late 199s levels. [Muted Bank ETF Expectations]

An improving U.S. economy could foster increased borrowing and financing by businesses, large and small, across the U.S. while benign mortgage rates could also provide a lift to the mortgage lending operations of regional banks.

Investors have added $280.1 million to KRE and $73.2 million to KBE since the start of the current quarter.

SPDR S&P Regional Banking ETF