Shares of automakers have struggled all year, but they began to drop sharply in June as concerns about the trade war mounted ahead of a wave of tariffs on imports to the United States and China.



So far in 2018, auto and auto-parts makers — as measured by the S.&P. index tracking the sector — are down more than 25 percent, vastly underperforming the broad stock market. On Monday, they fell 0.3 percent.

Investors in the sector are looking at a weaker Chinese economy, rising interest rates, and steel and aluminum import tariffs and worrying about what they mean for the car business.

China, the world’s largest a uto market, has “slowed down quite a bit,” said Itay Michaeli, United States auto industry analyst with Citi.

Back in the United States, auto sales, which had been a bright spot for the American economy, are also slowing. Through September, American auto sales were on track to be 4 percent lower than last year.

Rising interest rates could make matters worse. Rates on new four-year auto loans are above 5 percent for the first time since 2012, for example, which will make monthly payments on cars less affordable.

Investors will get more data points to consider soon: Ford is scheduled to report earnings on Wednesday morning. Its stock is down more than 30 percent this year as the company has announced a work-force reorganization in the face of stagnant sales.

General Motors, the largest American automaker by sales, will report its results on Oct. 31.