NEW YORK: Wall Street stocks were little changed on Wednesday as markets largely shrugged off disappointing results from Caterpillar and Boeing and a US antitrust probe into technology giants.

Investors were also keeping an eye on high-stakes congressional testimony from former Special Counsel Robert Mueller on Russian meddling in the 2016 US elections, part of a news-jammed session during peak earnings period.

About 40 minutes into trading, the Dow Jones Industrial Average was at 27,267.70, down 0.3 percent.

The broad-based S&P 500 was up less than 0.1 percent at 3,006.61, while the tech-rich Nasdaq Composite Index gained 0.1 percent to 8,260.88.

Technology giants were under scrutiny after the Justice Department announced it would begin an antitrust review of major online platforms to determine if they have "stifled" innovation or reduced competition.

Amazon fell 0.7 percent, Google parent Alphabet dropped 1.1 percent and Facebook 1.3 percent, while Apple was flat.

Art Hogan, chief market strategist at National Securities, said investors were taking a wait-and-see view of the probe, in part because any action by the government to break up one or more of the giants would take time.

"These things take years, not weeks," Hogan said. "It's going to change several large companies perhaps, or perhaps not."

Caterpillar dived 4.5 percent after reporting second-quarter earnings that missed analyst expectations and signaling full-year profits would be on the low end of its range, citing higher costs and weak activity in China and some other markets.

Boeing dropped 1.3 percent as it reported a $2.9 billion loss in the second quarter, its biggest ever, following the 737 MAX grounding.

The company also pushed back expectations for launching the 777X, a new long-distance plane. —AFP