• Salesforce falls after slashing profit, revenue outlook
  • Nordstrom dives after reporting quarterly loss
  • Indexes down: Dow 1.06%, S&P 0.71%, Nasdaq 0.12%

Wall Street's main indexes retreated on Friday as investors were cautious ahead of a US response to China's national security law on Hong Kong that threatens to take some shine off another month of strong gains for the stock market.

President Donald Trump, who has warned of a tough response to China's move, is expected to hold a news conference at 2 p.m. ET (1800 GMT).

“It is a pullback in front of what is likely to be pretty bipartisan and hawkish remarks from the president," said Bob Shea, chief executive officer of TrimTabs Asset Management in New York.

“I'm not surprised and it's happening at a time when markets are short term over bought, meaning due for some corrective action."

Despite worsening relations between the world's two largest economies amid the coronavirus crisis, expectations of a quick post-pandemic recovery in the economy have driven the S&P 500 about 37% higher from its March lows as it heads for a second straight month of gains.

The benchmark index is now about 11% below its Feb. 19 record high.

Federal Reserve Chair Jerome Powell, while speaking in a webcast organized by Princeton University on Friday, reiterated the US central bank's promise to use its tools to shore up the economy amid the coronavirus pandemic.

Financials were the biggest drag on the benchmark index after posting their best performance among all major S&P sectors this week. All the top sector indexes were also in the red.

At 12:46 p.m. ET, the Dow Jones Industrial Average was down 269.88 points, or 1.06%, at 25,130.76, the S&P 500 was down 21.44 points, or 0.71%, at 3,008.29. The Nasdaq Composite was down 11.55 points, or 0.12%, at 9,357.44.

A day after Trump signed the order threatening social media firms with new regulations over free speech, Twitter Inc hid a tweet from the President and accused him of breaking its rules by “glorifying violence".

Twitter shares were down 3.3% while Facebook Inc fell 0.4%.

Upscale department store chain Nordstrom Inc slumped 11.3% after it reported a near 40% fall in quarterly sales due to pandemic-led store closures.

Salesforce.com Inc slipped 5.2% as the cloud-based business software maker cut its annual revenue and profit forecasts.

Declining issues outnumbered advancers for a near 2-to-1 ratio on the NYSE and ratio on the Nasdaq.

The S&P index recorded nine new 52-week highs and no new lows, while the Nasdaq recorded 38 new highs and 12 new lows.