About 20 minutes into trading, the Dow Jones Industrial Average stood at 26,222.03, up 0.2 percent.

The broad-based S&P 500 advanced 0.4 percent to 2,877.90, while the tech-rich Nasdaq Composite Index jumped 0.7 percent to 7,901.19.

The gains were like a sequel to Monday's heady session that lifted major US indices by more than one percent. Markets paused on Tuesday, with the S&P 500 ending flat.

Key drivers of optimism include dovish US monetary policy and rising confidence that Beijing and Washington will hash out a major trade agreement that averts higher tariffs.

Analysts pointed to a report in The Financial Times that said the United States and China had resolved most issues and that trade talks resuming Wednesday in Washington could be "potentially climactic."

Investors shrugged off figures from payrolls firm ADP that the United States added just 129,000 jobs in March, much lower than the 178,000 economists had been expecting.

The report comes ahead of Friday's more important Department of Labor jobs data for March.