Wall Street pared gains as Donald Trump addressed the nation after being sworn in as the 45th president of the United States.

Ahead of Mr Trump's speech, the Dow Jones industrial average was up 93 points, or 0.5 per cent, to 19,82 shortly after open. The Standard & Poor's 500 index gained 11 points, or 0.5 per cent, to 2,274. The Nasdaq composite index added 27 points, or 0.5 per cent, to 5,568.

In his inauguration speech, Trump echoed protectionist comments he made in the past and called for measures to support American workers.

JP Morgan's global market strategist, Gabriela Santos, said markets drifted lower as Trump emphasised 'America First'.

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"The best place to see this happen was with the Mexican peso today. It took a very big dive during his speech," said Santos.

The market has been choppy in recent weeks following multiple records in November and December as investors weigh the likelihood of promised tax cuts and regulatory rollbacks.

Ms Santos told News Corp Australia that US equities markets are now focusing on some of the policy implementation and looking for more details.

Federal Reserve Chairwoman Janet Yellen said on Wednesday that the Fed would monitor the Trump administration's fiscal policies and take action if they cause the economy to grow too fast, potentially putting upward pressure on inflation.

"We are at a point where many economic policy changes are under consideration and of course we will closely follow what happens with economic policy," she said in a question-and-answer session following a speech.

The dollar has climbed since November on bets Trump's fiscal policies would fan inflation and force the Fed to raise borrowing costs.