Trading on Israel's Tel Aviv stock exchange was temporarily halted on Sunday after the market fell six percent at the open on news of a US credit rating downgrade, Israeli public radio reported. Trading opened as normal on Sunday, the first day of Israel's working week, but mandatory suspensions went into effect minutes into the session as the stock exchange plunged. The leading TA-100 indice was down 5.73 percent at 988.24 points by the time trading was halted, while the blue-chip TA-25 had fallen 5.42 percent to 1,092.41, according to the Tel Aviv Stock Exchange website. The session was the first on the Israeli bourse since Standard & Poor's rating agency said it was downgrading the United States' credit rating to AA+ from the top notch triple-A. The announcement panicked international markets and was criticised by Washington as unjustified. But S&P argued US leaders were becoming less able to get to grips with the country's huge fiscal deficit and debt load. The agency also gave a negative outlook for the US, saying there was a chance its rating could be cut again within two years if progress is not made to reduce the government budget gap. In Israel, the stock market plunge also came a day after massive nationwide protests over the high cost of living and income disparity in the Jewish state. Prime Minister Benjamin Netanyahu has pledged reforms to ease living costs, but has warned the broad reforms favoured by protesters could throw Israeli into a financial crisis.