(Reuters) -- Activist investor Carl Icahn disclosed a stake in Xerox Corp, and called the printer and copier maker's shares "undervalued", sending its shares up 7.6 percent in extended trade.

The billionaire revealed a 7.13 percent stake in Xerox in a securities filing on Monday, making him the second-largest shareholder of the 109-year old company.

Vanguard Group Inc, with an 8.37 percent stake, is the company's top shareholder, according to Thomson Reuters data.

Icahn, who recently took stakes in American International Group and Freeport-McMoran Inc, said he would look at getting representation on Xerox's board, as well as pursuing strategic alternatives.

"We are aware that Carl Icahn has made an investment in the company," Sean Collins, a Xerox spokesman said.

"Xerox welcomes open communications with shareholders and values constructive dialogue," Collins said.

The company, whose shares have fallen more than 22 percent this year, is trying to turnaround itself, shifting focus to software and services as corporate customers cut printing costs and consumers shift to mobile devices.

It reported its first net loss in five years in October, which prompted it to review its businesses and capital allocation options. The company, however, said it is not looking for a sale.

Xerox shares were trading at $11.56 in after market trading on Monday.

(Reporting by Anya George Tharakan and Arathy S Nair in Bengaluru; Editing by Anil D'Silva and Siddharth Cavale)