HONG KONG (MarketWatch) -- Hong Kong shares crumbled early Tuesday, sending the benchmark indexes more than 6% lower in opening trades after a heavy toll on Wall Street overnight in the wake of Standard & Poor's downgrade of U.S. debt. The Hang Seng Index HSI, +0.78% slumped 6.9%, or 1,413.19 points, to 19,077.38, and the Hang Seng China Enterprises Index gave up 7.5% to 10,282.69. The tumble sent the benchmark index into a so-called bear territory, with losses totaling more than 23% from its Nov. 8 high of 24,988.57. All Hang Seng Index constituents were deep in negative territory, with the resources sector among the worst hit. Aluminum Corp. of China Ltd. ACH, +0.77% 2600, -0.62% dived 9.7% and Cnooc Ltd. 883, -0.53% CEO, +0.24% plunged 10.9%. Heavyweight HSBC Holdings PLC HSI, +0.78% alone contributed a loss of more than 200 points for the benchmark index, with its 8.2% slump. China's Shanghai Composite SHCOMP, -0.19% fell 2.9% to 2,452.35.