US equity indexes traded mixed while most government bond yields rose as investors weighed the impact of President Donald Trump's auto tariffs and the economy unexpectedly grew above expectations in Q4.

The Nasdaq Composite rose less than 0.1% to 17,905.5 after midday on Thursday. The S&P 500 was nearly unchanged at 5,712.8. The Dow Jones Industrial Average fell 0.2% to 42,391.3. Technology and energy were among the steepest decliners intraday. Consumer discretionary, home to Tesla (TSLA), and consumer staples led the gainers.

Late on Wednesday, Trump unveiled a permanent 25% tariff on all imports of cars and light trucks into the US, effective April 2. Canadian Prime Minister Mark Carney is convening a cabinet meeting Thursday, Scotiabank said in a note.

Carney said the US auto tariffs are a "direct attack" on Canada and auto sector employees, and that Canada-US ties are "in the process of being broken." Responding to a question whether Canada would retaliate, Carney said "yes, it will happen soon." He went on to say that "we have options. We can introduce retaliatory tariffs."

Most US Treasury yields rose intraday, with the 10-year yield up 3.3 basis points to 4.37%. The ICE US Dollar Index fell 0.3% to 104.29.

Meanwhile, Tesla will be the automaker least impacted by US President Donald Trump's 25% tariffs on car imports, while General Motors (GM) and German carmakers will be the most negatively impacted, RBC Capital Markets said in a note. While Ford (F) and Stellantis (STLA) may be negatively hit, "Tesla could benefit meanwhile, given domestic production and competition from imports into the US."

Tesla shares rose 3.7%, among the top performers on the S&P 500 and the Nasdaq. General Motors shares slumped 6.8%, the steepest decline on the S&P 500.

In economic news, US gross domestic product growth was revised up to 2.4% for Q4 from a 2.3% increase in the previous estimate, compared with expectations for no revision in a survey compiled by Bloomberg. GDP grew 3.1% in Q3.

West Texas Intermediate crude oil futures rose 0.2% to $69.79 a barrel.