Gains in auto lending and equipment financing for businesses drove TCF Financial Corp. to its best quarterly profit since 2007.

The Wayzata bank company reported Friday that it earned $53.1 million in the second quarter, up from $38.9 million a year ago, a 37 percent increase.

The company, which runs Minnesota's third-largest bank by deposits and employs 3,000 people in the state, is reaping the benefits of a 2012 shift in strategy. It diversified from its traditional reliance on consumer banking to add a national auto finance business and some specialty lending operations.

"This is kind of the third reinvention in my career here," TCF Chairman William Cooper told analysts. "The truth is, you're never done in terms of this constant reinvention."

Cooper told analysts that the moves are paying off. Auto financing at the bank is up 70 percent over the past 12 months. TCF said it has partnerships with 9,500 auto dealerships and is adding 500 more each quarter.

"In the auto business, we're doing business with more dealers and deeper into more dealers," Cooper said.

When it comes to leasing and equipment financing, Cooper said the growth reflects "deeper penetration" with existing customers. The bank is helping golf cart and lawn mower dealers finance their inventory, said Terry McEvoy, an analyst with Sterne Agee.

"I think you have to give management a lot of credit for recognizing that their business model had to change, and then changing it," ­McEvoy said. "The company has transitioned itself."

TCF has helped soften concerns about a national subprime boom in auto lending by selling many of its lower-credit-score loans to other financial institutions, McEvoy said. But the rise in auto lending is still a concern in the banking industry.

"It's something that we will be monitoring going forward," he said.

For TCF, revenue was $310.1 million, up 2.7 percent from a year ago. Net interest income rose 2 percent compared with a year ago. The firm's net interest margin was 4.65 percent, down from 4.72 percent a year ago. That fell slightly in part because of heavy competition in the banking industry for loans.

The company's profit amounted to 29 cents a share, topping analysts' forecasts of 27 cents. TCF shares were up 1 percent in afternoon trading Friday.

This spring, the bank announced that it was exiting the TCF Tower and Bank Building in downtown Minneapolis and moving about 1,500 employees to a new campus in Plymouth. The exit will shrink TCF's presence in downtown Minneapolis to a single branch.