Mengniu Dairy saw the biggest fall in its share price for more than two years on Thursday, in Hong Kong trading, over concerns about soaring marketing costs and leaner profits due to fierce competition.

Stock in China Mengniu Dairy Co Ltd, the second-largest dairy producer in the country, at one point fell by 8.16 percent before closing at HK$35.45 ($4.57), down 6.71 percent, the biggest single-day loss since December 2011.

It was the worst performer in the benchmark Hang Seng Index, which dropped 0.7 percent.