US benchmark equity indexes closed higher on Wednesday, moments before the Trump administration announced new duties.

The Nasdaq Composite increased 0.9% to 17,601.1, while the S&P 500 rose 0.7% to 5,671. The Dow Jones Industrial Average was up 0.6% to 42,225.3. The consumer discretionary sector posted the highest gains, while consumer staples had the steepest decline.

US Treasury yields were higher, with the 10-year rate gaining about 1.1 basis points to 4.2% and the two-year rate up 3.1 basis points to 3.9%.

May West Texas Intermediate crude oil increased 1.4% to $72.20 a barrel on Wednesday.

President Donald Trump announced a blanket tariff of 25% on all foreign-made automobile imports at a White House event. Trump has touted it "liberation day in America!"

The implementation of 25% auto tariffs is expected to drive significant price increases leading to demand destruction of up to 3.2 million vehicles annually and a potential 15% to 20% reduction in vehicle sales, BofA Securities said in a note Wednesday.

In economic news, US private sector employment growth exceeded Wall Street's estimates for March, while pay gains decelerated, according to Automatic Data Processing (ADP) data.

"Despite policy uncertainty and downbeat consumers, the bottom line is this: The March topline number was a good one for the economy and employers of all sizes, if not necessarily all sectors," ADP Chief Economist Nela Richardson said.

Mortgage applications in the US declined last week for the third straight week as refinancing activity cooled, the Mortgage Bankers Association said.

In company news, Tesla (TSLA) shares jumped 5.3%, among the top gainers on the S&P 500 and the Nasdaq. Chief Executive Elon Musk will be stepping down in the coming weeks from his roles within the Trump administration, Politico reported, citing sources.

CarMax (KMX) rose 4.9%. The company is well-positioned for the upcoming tariffs of the Trump administration, with potentially a path to 2026 earnings of as much as $6 per share in a bull case scenario, Wedbush said in a Tuesday note.

ConnectM Technology Solutions (CNTM) shares surged past 51% after the firm said it has received a non-binding buyout proposal from its three largest institutional investors, valuing the company at about $46.5 million.

Altria (MO) was the worst performer on the S&P 500, down 2.9%, as Deutsche Bank downgraded its rating on the stock to hold from buy.

Gold gained 0.6% to $3,163.3 per troy ounce, while silver was up 0.8% to $34.57 per troy ounce.