The Dow Jones Industrial Average hit a record high on Thursday, bolstered by an upbeat weekly jobless claims report, while shares of vaccine makers fell after President Joe Biden backed plans to waive patents on COVID-19 shots.
Lifted by Apple Inc, the S&P 500 rose after a Labor Department report showed initial claims for state unemployment benefits totaled a seasonally adjusted 498,000 for the week ended May 1 compared with 590,000 in the prior week.
Investors were awaiting a more comprehensive non-farm payrolls report on Friday for clues on the strength of the labor market and potentially the U.S. Federal Reserve's stance on monetary policy.
"Investors are encouraged by the low-interest rates and the stimulus that the government is putting into the economy. We're also seeing substantial increases in economic projections and earnings forecasts," said Sam Stovall, chief investment strategist at CFRA Research.
Pharmaceutical companies dropped after the White House said Biden made the decision to back a proposed waiver for COVID-19 vaccine intellectual property rights.
Shares in Pfizer Inc, Moderna Inc, Johnson & Johnson and Novavax Inc, all involved in the making of COVID-19 vaccines, fell between 0.2% and 1.7%.
The S&P 500 healthcare sector index slipped 0.5%, while the Nasdaq biotechnology index dropped about 1%.
Moderna's shares cut some losses after it said countries around the globe would continue buying its COVID-19 vaccine for years even if patents on the shots are waived.
Microsoft Corp, Apple and Amazon.com Inc gained under 1% each.
The Dow Jones Industrial Average was up 0.46% at 34,386.31 points, while the S&P 500 gained 0.17% to 4,174.58.
The Nasdaq Composite dropped 0.41% to 13,526.47, pulled lower in part by a 1.9% dip in Tesla.
Costco Wholesale jumped 2% after the retailer said late on Wednesday that its April sales surged 33.5%. That rally helped push the S&P 500 consumers staple index up 1%.
Regeneron Pharmaceuticals Inc rose 3.5% after the drugmaker reported a better-than-expected quarterly profit and said it expected demand for its COVID-19 antibody therapy to hold up.
Uber Technologies Inc fell 8.5% after it signaled it would pay drivers more to get cars back on the road as the pandemic recedes, and disclosed a $600 million charge to provide UK drivers with benefits.
Declining issues outnumbered advancing ones on the NYSE by a 1.19-to-1 ratio; on Nasdaq, a 2.18-to-1 ratio favored decliners.
The S&P 500 posted 106 new 52-week highs and no new lows; the Nasdaq Composite recorded 96 new highs and 134 new lows.