BEIJING-- China's stock market continued to tumble Tuesday by opening 2.33 percent lower amid growing market fears of a double-dip recession after US credit rating downgrade.

The benchmark Shanghai Composite Index plunged 2.33 percent to open at 2,468.03. The Shenzhen Component Index opened 2.7 percent lower at 11,007.55.

The global financial market rattled after rating agency Standard & Poor's downgraded U.S. credit rating from AAA to AA+ on Friday. The US stocks experienced a free-fall overnight, with the Dow Jones industrial average lost 634.76 points, or 5.55 percent, to 10809.85.