New York CNN  —  A massive port strike is threatening America’s delicate supply chains. The Federal Reserve is rushing to prevent unemployment from spiking. And the race for the White House is coming down to the wire. Yet investors remain unrelentingly bullish, bidding the US stock market further into uncharted territory. The S&P 500 has scored 43 record highs so far in 2024. The latest milestone on Monday left the benchmark index up 20.8% on the year. That’s the strongest start to a year since