NEW YORK - Ford Motor Co. will regain an investment-grade credit rating sooner than the company expected, CEO Alan Mulally said Wednesday.

Ford, which borrowed more than $23 billion in 2006 before credit markets froze, is “paying the money back now, and we're going to be back to investment grade a lot sooner than what we thought,” Mulally said at an event with the Wings Club, an aviation group in New York, reported Bloomberg.

Since arriving from Boeing Co. in 2006, Mulally has revived Ford by expanding the namesake brand and improving vehicle quality. The automaker earned $4.7 billion in the year's first six months, its largest first-half profit since 1998.

Ford's finance arm, Ford Motor Credit Co., sold $1 billion of five-year notes Tuesday at interest rates that signal its investment-grade rating may be restored, said Greg Petryszyn, a fixed-income analyst at Minneapolis-based Thrivent Financial.

Standard & Poor's raised the second-largest U.S. automaker's credit rating last month two steps to B+, the fourth level below investment grade. Ford lost its investment-grade rating in 2005. Moody's Investors Service rates Ford B1, also the fourth level below investment grade.

Sales of redesigned models such the Taurus and Fusion sedans have helped boost the automaker's U.S. sales 17 percent this year through August, doubling the industrywide gain of 8.4 percent.

Mulally said in an interview that Ford hasn't provided a specific time frame for returning to investment grade, which is level Baa3 or above at Moody's and BBB- at S&P.

“We're going to be solidly profitable and generate positive free cash flow, and we will continue to improve our balance sheet and get back to investment grade,” he said.

Chief Financial Officer Lewis Booth said in March that Ford was “some years away” from regaining an investment-grade rating.

Ford Motor Credit is the second-biggest issuer of high- yield corporate debt this year, behind Ally Financial Inc., the auto and home lender majority owned by the U.S. Treasury, Bloomberg data show.