What happened?
It's fourth quarter and fiscal 2015 results season for many of the nation's banks. One fresh earnings report was delivered this week by regional lender Comerica (NYSE: CMA). For its Q4, the bank's revenues came in at just over $700 million, a 10% improvement over the same period a year ago. On the other hand, net profits slid by 13% to $130 million, or $0.71 per diluted share.

Both top and bottom lines modestly beat the analysts' average estimates, which anticipated $692 million in revenue and per-share profit of $0.69.

For the full year, total revenue was $2.7 billion, which bettered the 2014 tally of $2.5 billion. Net profit, however, slid by 10% to $529 million.

Does it matter?
Comerica is a lender that has many clients involved in the oil industry in Texas. Needless to say, that's an increasingly risky proposition in these days of sharply lower oil prices. This has compelled the bank to set aside more for potential loan losses, a pile that now amounts to $634 million, against $594 million a year ago. Nonperforming loans, meanwhile, jumped 31% on a year-over-year basis to $379 million.

All in all, Comerica's results weren't bad, but its involvement in energy sector lending is a concern. Investors would do well to watch how its credit quality is affected by developments in that business. Stubbornly low oil prices will, of course, have a strong impact on the viability of the entities that Comerica and peers like Texas Capital Bancshares have loaned money to.