NEW YORK (MarketWatch) -- Gold futures edged higher Friday in light trading following the Thanksgiving Day holiday, rising for a fourth straight week and ending the month with their biggest monthly gain in nine years. Gold for December delivery rose $7.70, or 1%, to close at $816.20 an ounce on the Comex division of the New York Mercantile Exchange. It rose 3.1% this week. In the month, gold advanced 14%, the biggest percentage gain since September 1999.