As a presidential candidate, Donald Trump liked to call himself "tariff man." Now that he's back in the White House, he's living up to his self-given nickname.

Trump has levied 10% tariffs on imports from China. He has announced plans to implement reciprocal tariffs on all U.S. trading partners. The president intends to impose 25% tariffs on all aluminum, steel, automobiles, pharmaceuticals, and computer chips imported to the U.S. And while a 25% tariff on all imports from Canada and Mexico was temporarily delayed, Trump stated this week these tariffs "will go forward."

The looming prospect of a trade war between the U.S. and major trading partners is bad news for quite a few stocks. I predict three, in particular, will be big losers in 2025 due to Trump's tariffs.

1. General Motors

Shares of General Motors (GM 0.30%) are already down by a double-digit percentage year to date. This decline has occurred despite the big automaker reporting better-than-expected fourth-quarter results in January. What's going on? Several factors are at play but concerns about Trump's tariffs especially stand out.

I think investors are right to be worried. GM exports more light vehicles made in Mexico to the U.S. than any other carmaker by far. Although most of the company's assets are in the U.S., a significant amount (12%) are in Mexico.

But Mexico isn't the only problem spot for General Motors. The company also has major facilities in Canada and China. In addition, GM has joint ventures in Canada and China, including some that focus on battery manufacturing and raw material sourcing.

"With respect to possible tariffs, we are working across our supply chain, logistics network, and assembly plants so that we are prepared to mitigate near-term impacts," GM CEO Mary Barra said in the company's Q4 earnings call in January. GM probably will be able to take some steps to reduce the negative impact of the tariffs. However, I nonetheless predict the auto stock will be one of the major losers from Trump's existing and proposed actions.

2. Lenovo Group

Lenovo Group (LNVG.F -10.98%) (LNVGY 0.48%) ranks as the world's largest PC maker. Its stock has been a big winner so far this year, with shares jumping more than 30%. However, Lenovo's prospects going forward might not be so great for one simple reason: It's a Chinese company, headquartered in Hong Kong.

Roughly 34% of Lenovo's total revenue is made in North America, according to Statista. Although the company doesn't provide details about sales in specific North American markets, it's fair to say that the lion's share of that amount is generated in the U.S.

Of Lenovo's 11 manufacturing locations, four are in China and two in Mexico. The company's other facilities are in Brazil, Hungary, India, Japan, and the U.S. Sure, Lenovo could ramp up production in its U.S. facility and/or try to ship more units from its facilities that aren't in China or Mexico. However, Trump's tariffs will almost certainly hurt.

It's important to remember, too, that before he returned to the White House Trump pledged to impose much steeper tariffs of 60% on imports from China. Notably, Robert Lighthizer, U.S. trade representative in Trump's first term and an unofficial advisor to the president, believes that China presents "an existential threat" to the U.S. He thinks higher tariffs are needed for Chinese imports. If Trump agrees, the impact on Lenovo's business from tariffs could be even worse.

To be fair, Lenovo CEO Yuanqing Yang doesn't think tariffs will hurt his company's business very much. He even went as far as saying in the recent earnings call that tariffs are "probably an advantage for Lenovo." Maybe Yang is right, but I wouldn't bet on it.

3. Magna International

Like GM, Magna International (MGA -0.34%) is already proving to be a disappointment for investors this year. Shares of the Canadian automotive supplier have fallen roughly 8% year to date and have plunged around 30% during the last 12 months. I won't be surprised if the misery continues in 2025 as a result of Trump's tariffs.

Magna specifically highlighted "increasing trade protectionism" as a risk factor in its 2024 third-quarter update. Without naming Trump, the company said, "One candidate's platform includes the potential imposition of significant tariffs on all U.S. trading partners, which could escalate into a global trade-tariff war."

The company is a major supplier to multiple automakers, including the "big three" in the U.S. -- GM, Ford, and Stellantis (formerly Chrysler). Anything that hurts these auto giants (and tariffs will hurt them) will hurt Magna, too.

An important caveat

My prediction that Trump's tariffs will cause GM, Lenovo, and Magna to be big losers in 2025 comes with an important caveat: I'm assuming the tariffs will remain in place. However, that assumption could prove to be wrong.

If many economists are correct in their forecasts that inflation will rise as a result of tariffs, the Trump administration could reverse course on its protectionist strategy. The White House has already delayed tariffs on Canada and Mexico once. It wouldn't be surprising if many of the tariffs mentioned earlier are only temporary ones.