US stock index futures fell as Congress failed to reach an agreement on a spending plan, forcing the government to shut down, leaving hundreds of thousands of federal employees unable to work. The government shutdown may disrupt the 14% rise in the S&P 500 index this year and may delay the release of key economic data, including the employment report scheduled for Friday. Some analysts say that if the non-farm employment data is delayed, it will increase the uncertainty caused by the government shutdown, and volatility is expected to increase after entering the new quarter.