But the recent market drop could portend problems. In 2018, a hefty dose of fiscal stimulus, in the form of tax cuts, allowed the United States to shake off the growth worries in China, Europe and the rest of the world. It won’t have the same potency next year, leaving the American economy and stocks more vulnerable to a range of risks, including a slowing global economy and continued rate increases by the Federal Reserve.

“I think there are very clear signs that investors are beginning to worry about weaker growth in the coming year or so, and how that’s going to feed through to corporate earnings,” said Michael Pearce, senior United States economist with Capital Economics.

Mr. Trump, on Tuesday, pointed to the health of the economy and instead blamed the Fed for contributing to the sell-off. Mr. Trump, who has taken credit for the rising stock market, has been critical of the rate increases, saying they undermine growth.

“I would like to see the Fed with a lower interest rate,” he said. “I think the rate is too high.”

Until recently, investors were willing to ignore the domestic political dramas, geopolitical turmoil and other issues clouding the outlook for American companies. Now they appear jittery, selling stocks at small signs that vague risks may become realities.

So far this year, strong growth and deep corporate tax cuts have supercharged corporate profits. Once all the results are tallied up, the third-quarter earnings for companies in the S&P 500 are expected to be up more than 28 percent from a year earlier — outpacing previous quarters, according to the financial data company Refinitiv.

But those numbers haven’t satisfied the markets. Investors have instead grown concerned about risks they face both from continued economic strength and, alternatively, an economic slowdown. Either path could upend a nearly decade-long rally that has lifted the S&P 500 nearly 300 percent.

Strong economic growth at home would most likely mean a prolonged rise in interest rates and rising costs in areas like wages, which would hurt corporate profitability. Weaker growth abroad would cut into sales.