First Horizon National

(FHN) - Get Report

says it plans to replace its chief financial officer, Marty Mosby.

The Memphis, Tenn., financial services company says the 18-year company veteran will help run its capital markets and investment banking business, FTN Financial.

Mosby will "focus on developing additional strategies" to improve revenue at the unit, and report to its president, Mark Medford, First Horizon says.

Mosby, who turns 43 Saturday, has been the company's CFO for the past three years. He will stay on as CFO until a successor is in place and complete year-end financial filings.

First Horizon, which has $37.5 billion in assets, plans to hire an undisclosed search firm to find a replacement for Mosby.

The flat yield curve has crimped First Horizon's mortgage banking and capital markets business. In the first quarter, it had as many as 14 one-time items wounding earnings, including cost-cutting initiatives and a balance-sheet repositioning. Though the company is valiantly making an effort to push through the tough banking environment and second-quarter earnings were improved, it is still trudging along.

Mosby says his position change is not related to difficulties First Horizon has been having as a result of the flat yield curve.

"It's disconnected completely," says Mosby. "It's a decision that I personally have made to take a different path in my career, which I have really been planning on for long time. It's a chance for me to go out and make a contribution to one of the three major businesses of our company."

Shares of First Horizon fell 68 cents Friday to $38.47.