The Nasdaq Composite and S&P 500 Index each reached a fresh intraday high on Thursday as bullish momentum surrounding the artificial intelligence industry helped offset lingering tariff concerns.

The tech-heavy Nasdaq (QQQ  ) rose above the flatline to 20,630.67 for the first time ever, while the broader market S&P 500 Index (SPY  ) added nearly 0.3% to settle at a new high of 6,280.46. The Dow Jones Industrial Average (DIA  ), meanwhile, climbed over 190 points to finish at 44,650.64.

President Donald Trump issued another new tariff late Wednesday, setting the U.S. import duty on copper to 50% effective Aug. 1. The president also announced the U.S. will impose a 50% tariff rate on Brazilian imports -- a massive jump from its original "Liberation Day" rate of 10% -- in response to a "very unfair trade relationship." Brazilian President Luiz Inácio Lula da Silva said Wednesday the country will respond based on its economic reciprocity laws.

Trump said that the new tariff rate was also partly in retaliation for the current trial against former President Jair Bolsonaro for his role in the alleged attempt to overturn his 2022 reelection loss, calling it "an international disgrace" in a letter shared in a Truth Social post.

The new tariffs follow a slew of updates to the Trump administration's trade policies this week, as Trump released a series of letters to nearly two dozen countries, including key trading partners Japan and South Korea, outlining new duty rates set to take effect Aug. 1.

"We expect inflation to accelerate over the coming months in large part due to tariff related price increases," Bank of America economist Stephen Juneau wrote in a Wednesday note. "But tariffs aren't the only reason to expect firmer inflation in the coming months; the rebound in stock prices is another."

In the news, MP Materials (MP  ) announced Thursday the Pentagon became its largest shareholder, buying $400 million of the rare earth mineral miner's preferred stock. The company owns the only operational rare earth mine in the United States at Mountain Pass, California, and CEO James Litinsky said the federal government's investment will accelerate the development of an end-to-end rare earth magnet supply chain. Rare earth minerals have become a focal point in trade negotiations between the U.S. and China.

"We understand that this partnership is ultimately on behalf of the taxpayers and our national security, and with that comes a great responsibility to get this down right," Litinsky told investors on a call Thursday morning. "Securing America's supply of rare earth materials and magnets is essential to our economic and national security."