The U.S. stock market set 36 all-time highs in 2025 through October — remarkable for an aging bull that entered its fourth year that month. The S&P 500 Index returned 17.5% over that period (21.5% in the 12 months since we published our 2025 Investing Outlook), and a cumulative 91% since the bull market began in October 2022.
So why do some investors feel like there's a piano tied with a fraying rope suspended above their heads? The risks they're worried about include sticky inflation and a weakening job market, continuing trade tensions and potential cracks in the credit markets. Above all, investors are leery of an artificial intelligence (AI) boom that brings to mind bubbles of markets past. Are these concerns just proverbial bricks in the wall of worry that bull markets like to climb? Or are they signposts of something more sinister?
