Up until January, investors were willing to pay high valuations for stocks because they expected corporate earnings to accelerate this year. But the best may already be behind us. Lori Calvasina, head of United States equity strategy at RBC Capital Markets, on Monday wrote that analysts now believe that earnings growth for this year likely peaked in the first quarter (at 23 percent over last year’s first quarter.) After such peaks, the stock market tends to remain weak for a while, she added.

Investors likely won’t have a big new jump in profits to look forward to. Earnings are expected to grow 10 percent next year, according to estimates compiled by Standard & Poor’s. Without sustained support from corporate earnings, investors may be more willing to sell stocks in response to geopolitical events.

And in the coming weeks, there will be plenty of potential trade war triggers. The Trump administration could decide to impose tariffs on steel and aluminum from a number of countries, including those in the European Union, when exemptions expire at the end of this month. Proposed tariffs on $50 billion of goods from China could also be imposed this month, and the White House could release details on a second batch of tariffs on $100 billion of Chinese products.

Since neither the European Union nor China looks close to caving to Mr. Trump’s threats, global trade tensions look set to escalate and a full-blown trade war is possible.

Investors may continue to hang tight, of course. The stock market is flat for the year, not a bad performance for a period in which the underpinnings of the international economic order are under assault.