Shares in Asia opened in negative territory today after mainland China saw a dramatic sell-off the previous day. In its biggest drop in eight years, the Shanghai Composite had tumbled more than 8 per cent on growth concerns.US stocks overnight took the cue from the insecurity in China and the Dow Jones fell to a five-month low.Asia's largest stock market, Japan's Nikkei 225 was 1 per cent down to 20,148.07 points in early today's trade.