Companies with the most to lose from Trump's tariffs

President Trump's decision to slap tariffs on steel and aluminum imports had an immediate effect on the stock market yesterday, driving the Dow 420 points lower and boosting U.S. steelmaker stocks. But several sectors that rely on steel and aluminum for raw materials are already feeling the heat from the tariffs, which go into effect March 5.

Construction

Accounting for 40% of steel demand, the U.S. construction industry is one of the world's largest, with "new construction" valued at around $1.16 trillion in 2016, per Statista. As the country's aging infrastructure begins to crumble, the sector is projected to grow to $1.42 trillion by 2021. These are the five largest American construction companies, per Engineering News-Record:

1. Bechtel — $32.9 billion (2016)
2. Fluor Corp. — $19.5 billion (2017)
3. Aecom — $18.2 billion (2017)
4. Turner Corp — $10.8 billion (2014)
5. CB&I — $10.7 billion (2016)

Automakers

Domestic automaker stocks dropped about 3% Wednesday following Trump's announcement. The industry accounts for 26% of U.S. steel demand, and even foreign carmakers with major manufacturing plants in America, like Toyota, are warning of "substantially' higher prices, per Axios' Dan Primack. These are the four biggest American automakers by revenue.

1. Ford — $156.8 billion
2. General Motors — $145.6 billion
3. Fiat Chrysler — $136.7 billion
4. Tesla — $11.8 billion

Energy

As Axios' Ben Geman reported, trade tensions between Trump and the oil-and-gas industries — which accounted for 10% of steel demand in 2017 — are boiling over in the aftermath of the tariff announcement. Pipeline companies specifically may be forced to cancel projects, since trade restrictions on steel would increase pipe costs 25%. Here are the five largest oil and gas companies in the U.S, according to 2017 revenues:

1. ExxonMobil — $186.3 billion
2. Chevron — $134.7 billion
3. Valero — $67.6 billion
4. Marathon Petroleum — $53.7 billion
5. Enterprise Products — $29.2 billion