Billionaire Kirk Kerkorian’s company says it plans to make a cash offer of $8.50 per share for up to 20 million shares of Ford Motor Co.

The offer price represents a 13.3 percent premium over Ford’s closing price on Friday.

Kerkorian’s Tracinda Corp. now owns 100 million Ford shares, or 4.7 percent of the outstanding stock. When the offer is completed, Tracinda’s stake will increase to 5.6 percent.

Tracinda says Ford’s first-quarter results reinforced that the company is having success in its turnaround efforts, despite the difficult U.S. economy. Tracinda says it believes the Dearborn, Mich.-based company will continue to “show significant improvements.”

The offer is not subject to financing.