REUTERS/Shannon Stapleton If the US government's shutdown lasts less than six or so weeks, the robust stock market will probably be fine. If the shutdown goes on longer than six or so weeks, according to economists, expect stocks to dip. But most economists didn't see the shutdown coming, and they estimate that both sides will negotiate eventually to avoid major harm to the economy. If the shutdown lasts just days or even a couple of weeks, the robust stock market that President Donald Trump has boasted about probably will emerge unscathed.