Hong Kong's Hang Seng index traded lower on Friday, pushed down by property shares as investors gathered news that two of the city's influential property magnates have been arrested. Hang Seng index dropped 0.26% or 53.81 points to 20,555.58. Sun Hung Kai Properties fell 13.1%, Henderson Land Development tumbled 2.5% and Wharf Holdings lost 2.9%. On the upside Bank of China added 1.6% as its earnings surpassed projections.