General Motors said on Tuesday that its profit in the second quarter fell by more than a third, after President Trump’s tariffs cost the company more than $1 billion.

G.M. was the second automaker in as many days to show the toll that the Trump administration’s trade policies are taking on the industry. Stellantis, the maker of Chrysler, Jeep and Ram vehicles, said on Monday that it lost 2.3 billion euros ($2.7 billion) in the first half of the year because of tariffs and other Republican policies.

G.M.’s profit for the quarter was $1.9 billion, the company said, down from $2.9 billion in the same quarter last year. Sales fell 2 percent, to $47 billion.

Mary Barra, G.M.’s chief executive, said in a letter to shareholders that the company is investing $4 billion to increase production in the United States of pickups and sport utility vehicles that would be less susceptible to tariffs.

“We are positioning the business for a profitable, long-term future as we adapt to new trade and tax policies, and a rapidly evolving tech landscape,” Ms. Barra said.