E-mini futures for the S&P 500 rose another 0.5% in early Wednesday trade.
A reality check then appeared to be setting in amid the ongoing coronavirus pandemic and a batch of discouraging US economic data, including jobless numbers. Drugmaker AstraZeneca has said its potential vaccine, being developed with Oxford University, was up to 90 per cent effective.
The United States has reported more than 12.7 million COVID-19 cases in total with the death toll from the disease exceeding 261,000 as of Wednesday afternoon, showed a tally by Johns Hopkins University.
Citi Research wrote in a note on Monday that herd immunity would not form until late 2021, boosting global gross domestic product growth by only 0.7% next year compared with an estimated 3% gain in 2022 as vaccination rates rise.
The S&P index recorded 12 new 52-week highs and no new lows, while the Nasdaq recorded 81 new highs and five new lows.
"The market overall has reached by most standards what we call overbought conditions, and that typically suggests that the market would need to digest the gains, perhaps pause a bit, and consolidate", said Quincy Krosby, chief market strategist at Prudential Financial.
Retailing (+1.05%), Technology Hardware & Equipment (+0.47%) and Household & Personal Products (+0.41%) sectors were the best performers, while Automobiles & Components (-2.82%), Energy (-2.42%) and Materials (-1.08%) sectors lagged behind.
US stocks rallied on Tuesday and the Dow breached the 30,000 level for the first time, as investors anticipated a 2021 economic recovery on coronavirus vaccine progress and the formal clearance for President-elect Joe Biden's transition to the White House.
The S&P 500 was down 0.27%, while the Nasdaq Composite was up 0.11%.
The rally was also supported by the likelihood that President-elect Joe Biden will formally appoint former Federal Reserve Chair Janet Yellen as his Treasury secretary.
The Dow rose as high as 30,116.51 during the session and the S&P 500 also closed at a record high.
The Commerce Department said USA consumer spending, the primary driver of the economy, rose by a sluggish 0.5% in October, the weakest gain since April when the pandemic first erupted. It was also optimistic about the incoming Biden government.
Ramos said those estimates may be overly optimistic and the economic benefits of vaccinations will not be apparent until the second half of next year, increasing chances that the recent US economic slowdown could worsen.
Brent futures gained 1.2% to $48.45 per barrel, a high last seen in early March.
The U.S. dollar inched down to 104.32 Japanese yen from 104.50 yen.