Wall Street has risen 2 per cent, led by the technology and healthcare sectors as investors breathed a sigh of relief following the US midterm elections and made bets that a divided Congress would be good news for equities.
Democrats won control of the House of Representatives on Tuesday, while President Donald Trump's Republican party expanded its Senate majority, pointing to the likelihood of political gridlock in Washington.
The S&P's biggest boosts came from the S&P technology sector and the healthcare stocks, with both indexes gaining 2.9 per cent. The consumer discretionary sector climbed 3.1 per cent, spurred by a 6.9 per cent rise in Amazon.com shares. Amazon provided the single biggest boost to the S&P 500.
'Now we're in an environment that people can understand again so they'll be willing to put some money back on the table. There was a little fear out there,' said Peter Tuz, president at Chase Investment Counsel Corp in Charlottesville, Virginia.
The Dow Jones Industrial Average rose 545.29 points, or 2.13 per cent, to 26,180.3, the S&P 500 gained 58.44 points, or 2.12 per cent, to 2,813.89, and the Nasdaq Composite added 194.79 points, or 2.64 per cent, to 7,570.75.
The CBOE Volatility Index, the most widely followed gauge of expected near-term gyrations for the S&P 500, finished down 3.55 points at 16.36, its lowest close in about a month.
While a divided Congress will make it harder for President Donald Trump to push through new legislation such as additional tax cuts, investors were not expecting a reversal of tax cuts and deregulation already enacted under Trump.
'This outcome probably provides the most paralysis for new policies,' said Brian Nick, chief investment strategist for Nuveen Asset Management in New York, adding that growth sectors such as tech and healthcare would continue to be strong.
'In a scenario where there's no (additional) fiscal stimulus and we're not experiencing severe growth concerns in terms of contraction, they're the best bet,' he said.
Some strategists said Democratic control of the House means that Trump will have a harder time gaining support for efforts to impose new regulations on Amazon.com.
But even as technology and healthcare stocks soared, several investors questioned whether the sectors could now be at risk of additional regulatory scrutiny.
Even after Wednesday's gains, the S&P 500 was 4 per cent below its record close in September, as investors kept their eyes on rising interest rates and the US-China trade war.
The Federal Reserve began a two-day monetary policy meeting on Wednesday, but no rate increase was expected when it releases its policy decision on Thursday. The Fed is expected to raise rates in December, at its last policy meeting of the year.
Health insurers Humana Inc, Anthem Inc and UnitedHealth Group Inc jumped to record highs as voters in three states approved expanding Medicaid programs for low-income people.
DaVita Inc jumped 10.9 per cent after California rejected a proposal to limit the rates that dialysis clinics can charge commercially insured patients.
Anadarko Petroleum Corp rose 5.7 per cent and Noble Energy Inc gained 4 per cent after Colorado voters rejected a tougher rule on oil and gas drilling, which spurred shares of companies operating in the state.
Advancing issues outnumbered declining ones on the NYSE by a 3.27-to-1 ratio; on Nasdaq, a 2.31-to-1 ratio favoured advancers.
The S&P 500 posted 35 new 52-week highs and three new lows; the Nasdaq Composite recorded 67 new highs and 71 new lows.
On US exchanges 8.0 billion shares changed hands compared with the 8.64 billion average for the last 20 sessions.