DOHA, Jan 2 (Reuters) - Qatari construction firm Investment Holding Group (IHG) will launch an initial public offer of its shares next week in a boost for the country's stock market, which has seen only two new listings since 2010.

The family-owned contracting and trading business will offer 49.8 million shares, or 60 percent of its capital, at a price of 10.1 riyals per share, the company said in a statement late on Sunday. That would make the value of the offer about 503 million riyals ($138 million).

IHG, a holding company which through its subsidiaries provides contracting, shipping, real estate and education services according to its website, will be the first family business in Qatar to list its shares on the exchange via an IPO, it said.

The shares will be offered through Commercial Bank COMB.QA between Jan. 8 and 22 to Qatari citizens and companies.

While state firms developed the energy sector in Qatar and other Gulf Arab countries, family-run businesses built much of the rest of the regional economy. They generate more than 80 percent of non-oil gross domestic product in the six-nation Gulf Cooperation Council, consultants PwC estimated.

Families have often been reluctant to take their companies public for fear of losing control and because of concern about how the Gulf's illiquid markets would value their shares.

But pressure to go public has been increasing; regulators want family businesses to list in order to deepen the markets, and listings can help the firms cope with increasing competition and the challenge of raising money in an era of low oil prices.

Ghanim al-Hodaifi, chairman of IHG's board of directors, said an IPO was an opportunity for Qatari family businesses to "to improve the management of share capital" and expand their shareholder bases.

(Reporting by Tom Finn; Editing by Andrew Torchia) ((Tom.Finn@thomsonreuters.com;))