Automaker shares sank on Thursday on news of weaker-than-expected January sales and forthcoming tariffs.

President Donald Trump said the US would soon impose new tariffs, or import taxes, of 25% on steel and 10% on aluminum.

The shares of major automakers fell on Thursday as investors received a double whammy of weak sales numbers and forthcoming tariffs.

The Detroit big-three - Ford, General Motors, and Fiat Chrysler - all reported declines in February sales from a year ago. Overall sales likely fell at an annualized rate of 16.9 million, down from 17.5 million last year, according to Bloomberg.

Also, President Donald Trump announced the US would soon impose new tariffs, or taxes, of 25% on steel and 10% on aluminum.

At 2 p.m. ET, GM shares were down 4.3%, Fiat Chrysler was down 3.3%, and Ford was 3.5% lower. The broader stock market also fell on news of the tariffs, with the Dow Jones industrial average shedding more than 500 points (about 2%).

In a meeting with executives from steel and aluminum producers, Trump said the tariffs would be rolled out next week to help bolster the US metal industries. But the American International Automobile Dealers Association, a trade group, has already come out against the move, saying it would make cars more expensive.

"These proposed tariffs on steel and aluminum imports couldn't come at a worse time," Cody Lusk, CEO of the American International Automobile Dealers Association, said in a statement on Thursday.

"Auto sales have flattened in recent months, and manufacturers are not prepared to absorb a sharp increase in the cost to build cars and trucks in America. The burden of these tariffs, as always, will be passed on to the American consumer. Car shoppers looking for a deal will instead find that they are paying a new tax to transport themselves and their families."