A Friday rally can’t hide the fact that the stock market is stuck in an ominous pattern—and it’s not clear what will shake it out. Indexes notched their worst weekly performances in months as markets were whipsawed on tariff news. The S&P 500 rose 0.6% on Friday but fell 3.1% on the week, its worst weekly showing since September. It’s now down 1.9% for the year. The Dow Jones Industrial Average fell 2.4%, and the Nasdaq Composite dropped 3.5%. The biggest problem is uncertain federal policy, which appears to be causing many businesses to hold off on making investment decisions….