Standard & Poor's Ratings Services downgraded five more North American banks late Tuesday, a move to better reflect a recalibration of its view of the banking sector. The downgrade is a result of the application of the revised bank criteria published on Nov. 9, rather than any sudden and striking changes in creditworthiness.

This is the second round of bank ratings changes from the S&P, and a muter one, compared with the massive stir the ratings agency caused when it downgraded 37 large financial institutions. The firm said a third and final round of re-evaluation is to be expected.

S&P downgraded the credit rating on the Northern Trust Corp. (NTRS) to "A+" from "AA-". The outlook remains stable.

The rating agency also lowered its long-term issuer credit rating on U.S. Bancorp (USB) to "A" from "A+".

PNC Financial Services Group Inc. (PNC) and BB&T Corp. (BBT) received a one notch cut in their long-term ratings respectively, to "A-" from "A".

In addition, S&P lowered its long-term issuer credit rating on Commerce Bancshares Inc. (CBSH) to "A-" from "A".