US open: Stocks continue to head south ahead of Fed speeches

As of 1530 BST, the Dow Jones Industrial Average was down 0.41% at 26,696.21, while the S&P 500 was 0.22% lower at 2,969.29 and the Nasdaq was trading just 0.01% softer at 8,097.18.

The Dow Jones opened 109.93 points lower on Tuesday after the previous week's strong jobs data dampened expectations that the Federal Reserve would cut interest rates by 50 basis points when rate-setters in the US next met at the end of July.

With interest rates in mind, investors were also waiting on potential remarks by Atlanta Fed President Raphael Bostic, who was due to speak at an event at Washington University, St.Louis, at 1910 BST.

Earlier, Powell delivered the opening remarks at a Boston Fed conference on Tuesday but, as expected, made no references to monetary policy ahead of his semi-annual testimony to the House Financial Services Committee on Wednesday.

However, in an interview with the Wall Street Journal, Philly Fed boss, Patrick Harker, reportedly said that the US economy was "strong" and that he did not envisage any interest rate cuts in 2019.

Coming just a few days after a much stronger-than-expected jobs report for June raised questions about the central bank's interest rate policy, market participants were keen for fresh insights into Fed policymakers' most current thinking.

On the trade front, talks aimed at ending the trade war between China and the US are set to resume as early as this week.

Larry Kudlow, director of the National Economic Council of the US and an advisor to Donald Trump, said at the end of last week that a face-to-face meeting was "on the cards", while on Tuesday, Reuters said negotiations would start this week with a phone call between US Trade Representative Robert Lighthizer, Treasury Secretary Steven Mnuchin and Chinese vice premier Liu He.

Elsewhere, the row between the UK and US over leaked diplomatic cables describing Donald Trump as "inept" escalated overnight as the president said he would not work with British ambassador Kim Darroch.

In a series of typically bombastic tweets, Trump also slammed outgoing UK Prime Minister Theresa May's handling of Brexit, calling it a "mess" and claiming she had ignored his advice on the subject.

On the data front, the National Federation of Independent Business' small business optimism index for June dipped to 103.3 - down from the 105.0 recorded in May and marginally above consensus estimates of 103.1.

Pantheon Macroeconomics' Ian Shepherdson said the most important number in the report was the subindex for selling prices, which rocketed to 17 from 10.

"The index usually is responsive to gasoline prices, which dipped last month, pointing to a two-point dip. Adjusted for the impact of gas prices, this is the highest reading for the selling price measure since November 2006, and it is consistent, if sustained, with core CPI inflation rising to 2.7% by next spring," he said.

"We assume this jump reflects the increase in tariffs on Chinese imports in May, from 10% to 25%, so we doubt it will reverse anytime soon."

The headline index, meanwhile, was pulled down by six-point drops in sales expectations and "good time to expand", and a four-point fall in capex plans.

Still on the data front, job openings fell in the US during the month of May, dragged down by declines in the construction and transportation industries.

Job openings slipped 49,000 to a seasonally adjusted 7.3m in May, according to the Labor Department in its monthly Job Openings and Labor Turnover Survey. The job openings rate dipped to 4.6% from 4.7% in April.

In corporate news, PepsiCo shares were down 0.49% in early trade despite topping estimates on strong snack and beverage sales, while jean maker Levi Strauss will post its latest figures later in the day.

Elsewhere, network gear maker Cisco Systems saw shares inch forward 0.25% at the bell after it agreed to buy optical component maker Acacia Communications for $2.6bn.