The Nasdaq composite rose to a record high close and other major indexes hovered near their own recent all-time highs in a session with thin trading volume.
A rally since late June has left the S&P 500 up nearly seven percent in 2016, with many investors weighing stretched valuations against expectations for continued low interest rates.
"We're probably going to consolidate and then head higher," said John Canally, chief economic strategist for LPL Financial.
"The odds of a US recession are low. The odds of a global recession are low. Central banks are cooperating."
The S&P 500 index's healthcare index rose 0.24 percent, helped by a 21.8 percent jump in Endo International after the company's quarterly profit beat estimates.
The CBOE volatility index, known as Wall Street's 'fear gauge', briefly fell to a one-year low of 11.02.
The Nasdaq Composite added 0.24 percent to end at 5,225.48 points, exceeding a record high set on Friday.
The Dow Jones industrial average edged up 0.02 percent to end the day at 18,533.05 points and the S&P 500 inched up 0.04 percent to 2,181.74.
Trading volume was low. About 5.99 billion shares changed hands on US exchanges, compared with the 6.48 billion daily average over the last 20 sessions.
Six of the 10 major S&P 500 indexes rose, led by a 0.24 percent increase in the consumer staples index.
Investors mostly shrugged off a report that US productivity unexpectedly fell in the second quarter, which could affect companies' ability to maintain recent robust hiring.
Canally said that risks weighing against greater stock gains included volatility caused by candidates' campaigns ahead of the November US presidential election and potential changes in expectations about the timing of future interest rate hikes.
Valeant jumped 25.43 percent after maintaining its full-year forecast and saying it would reorganise its business.
Microchip Tech rose 7.03 percent after the company's first-quarter revenue beat analysts' average estimate.
Advancing issues outnumbered declining ones on the NYSE by a 1.14-to-1 ratio; on Nasdaq a 1.31-to-1 ratio favoured advancers.
The S&P 500 posted 27 new 52-week highs and no new lows; the Nasdaq Composite recorded 116 new highs and 26 new lows.