Wall Street will test the theory that a moving object stays in motion in the coming weeks and months after the S&P 500 notched another all-time high on Sept. 10. The S&P 500's advance since this spring's tariff-tantrum meltdown has been impressive, with the benchmark index rallying over 30%. The gains have mostly come despite evidence that the U.S. economy is stumbling amid rising unemployment and inflation. Nevertheless, optimism that stimulus associated with the passage of the One Big Beautiful Bill Ac ...