The CBOE Volatility index dropped 7.6 percent to 9.77, its lowest since 1993 as investors took comfort from Macron's victory, as well as from strong quarterly reports in recent weeks.
A declining VIX typically indicates a bullish outlook for stocks, but the extreme lows the index has touched are sounding caution for some stock investors.
"It's been here before, but not much lower than this," said Donald Selkin, Chief Market Strategist at Newbridge Securities in New York. "It's signaling that something negative is in the works."
Seven of the 11 major S&P sectors dipped, with the materials index down 0.91 percent and energy rising 0.7 percent on the back of higher oil prices.
The euro hit a six-month high against the dollar after Macron comfortably defeated far-right nationalist Marine Le Pen who had threatened to take France out of the European Union.
"We remain largely constructive of the equity market and view that the path of least resistance is higher," said Bill Northey, chief investment officer at Private Client Group of US Bank.
The Dow Jones Industrial Average edged up 0.03 percent to end at 21,012.28 points and the S&P 500 gained 0.08 points, less than a hundredth of a percent, to end at 2,399.37. It briefly touched a record high of 2,399.94.
The Nasdaq Composite added 0.03 percent to 6,102.66.
With March-quarter reporting season nearly complete, S&P 500 earnings on average have grown 14.4 percent, and earnings for the June quarter are expected on average to increase 8.6 percent, according to Thomson Reuters I/B/E/S.
Suggesting US stocks remain expensive, the S&P 500 is trading at 17.8 times expected earnings, compared to its 10-year average of 14.2, according to Thomson Reuters Datastream.
Shares of Kate Spade jumped 8.31 percent after bigger rival Coach Inc said it would buy the handbag maker for $2.4 billion to increase its exposure to millennial shoppers. Coach shares rose 4.8 percent.
Straight Path surged nearly 33 percent after an unnamed telecommunications company raised its offer to buy the wireless spectrum holder for about $3.1 billion, trumping a bid by AT&T. Sources told Reuters that the bidder was Verizon .
Tyson Foods was the biggest S&P loser, down 6.08 percent after the meat processor reported a slump in quarterly profit.
Declining issues outnumbered advancing ones on the NYSE by a 1.23-to-1 ratio; on Nasdaq, a 1.22-to-1 ratio favored decliners.
The S&P 500 posted 44 new 52-week highs and 4 new lows; the Nasdaq Composite recorded 116 new highs and 58 new lows.
About 6.3 billion shares changed hands in US exchanges, below the 6.6 billion daily average over the last 20 sessions.