Wall Street just got a wake-up call. Friday’s punishing sell-off reminded everyone of the fragility of current record-level optimism in the market, especially when politics and policy collide. U.S. stocks took a monumental hiding on October 10 when President Donald Trump threatened an unnerving 100% tariff on Chinese imports, leading to the sharpest one-day drop since April. Consequently, the S&P 500 slid 2.7% to 6,552.51, with the Nasdaq tanking 3.6%, while the Dow lost 1.9%, wiping out nearly $2 trilli ...