Since the first mainland launch in March last year, 5,700 group-buying sites had sprouted, it said.An editorial on lingtuan.com said: “The group buying market is entering a cold winter … and it’s just beginning.” It cited a high level of poor service complaints as a reason for the closures.Citing an analyst, Hong Kong’s South China Morning Post reported on Friday that a lack of investment, keen competition and poor management were also factors.Group buying site tuan800.com reported that September saw large scale layoffs by well-known Chinese sites Wowo and Tuanbao, which are clones of Chicago-based Groupon.It said Wowo may cut 70 pct of its workforce, while Tuanbao, known to have invested 500 million yuan ($78.35 million) in advertising, would cut its headcount by half.In August, Groupon said it was cutting some underperforming staff at Gaopeng, a Chinese joint venture with Tencent Holdings Ltd. Gaopeng, has a small slice of the Chinese group buying market, trailing more popular players such as Lashou, Meituan, Wuwutuan. ($1 = 6.382 yuan)