chi-bank photo (3) Banks are still popular with net lease investors, but in the future they will be more cautious.

CHICAGO—Net lease investors have for some time considered bank branches one of the best investments on the market, pushing down the cap rates for these properties to historically low levels. In the past year, however, things have changed, and rates took a big jump upward, according to a new study by the Boulder Group, a net lease firm in suburban Chicago.