HOUSTON (Dow Jones)--Billionaire turnaround investor Wilbur Ross has built up a 7.5% stake in Exco Resources Inc. (XCO), nearly all of it since the Fort Worth company's chief executive announced he would try to take the natural-gas producer private.

Exco said in a regulatory filing that Ross and entities he controls have bought 15,882,301 shares this quarter. More than 96% of those shares were acquired after Chief Executive Douglas Miller announced a $4.4 billion bid to buy the company on Nov. 1, according to the filing.

Ross already held a 0.88% stake in Exco at the end of the third quarter through his WL Ross & Co. The shares he has acquired since Oct. 1 have a value of nearly $294 million at Friday's closing stock price of $18.51.

Miller's bid equates to $20.50 a share. Exco's board has formed a special committee to study the offer and hired Barclays Capital Inc. and Evercore Partners as its independent financial advisers.

In his own filing with securities regulators, Ross indicated that he would pursue talks with Exco's management, potentially regarding a merger, asset sales or acquisitions, changes to the company's financial policies or business structure, and that he may seek to exchange information under a confidentiality agreement.

Miller, who is also Exco's chairman, has twice taken the companies he's headed private. In 2003, he led a buyout of Exco shareholders and took the company public again in 2006. Prior to that, he took Coda Energy Inc., a Dallas oil and gas explorer, private.

In his Nov. 1 letter to Exco's board, Miller said he had discussed the latest bid with private-equity firms Oaktree Capital Management LP and Ares Management LLC, as well as billionaire oil tycoon T. Boone Pickens, who is on the Exco board.

Together, Oaktree, Ares and Pickens owned more than 27% of shares, while Miller and his management team control another 13%, according to FactSet Research. Miller owned more than 2% of Exco's stock at the end of the third quarter.

Exco has generally focused on acquiring established oil and natural-gas fields and squeezing additional output from them. Exco currently has production holdings in Texas, Louisiana, Pennsylvania and West Virginia.

The company said recently it would double spending in 2011 and ramp up drilling in its Texas and Louisiana shale formations with a 40% increase in output in mind.

-By Ryan Dezember, Dow Jones Newswires; 713-547-9208;

ryan.dezember@dowjones.com