Amazon has accounted for 27 percent of the S&P 500's gains in 2018, and the S&P 500 technology sector has fueled more than three-quarters of the index's advance, according to The Wall Street Journal.
Following Amazon are Microsoft, which has driven 13 percent of the S&P 500's gains, and Netflix, which has contributed 8.3 percent.
"When you see a Netflix or Amazon leading, it's not necessarily a great sign of investor confidence, since you know those names can always deliver growth no matter what's going on," Jack Ablin, founding partner and chief investment officer at Cresset Wealth Advisors, told WSJ.
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