Veteran fund manager Larry Glazer is worried too many investors are in the wrong trade.
His concerns stem from the crucial role big technology stocks are playing in the record rally. If investors don't diversify away from some of the year's biggest winners now, Glazer believes they're going to feel a world of pain.
"Ten names driving half of the return of the S&P 500 in the first seven months of the year. They want to hear that can continue because it's a neat and convenient story," the Mayflower Advisors managing partner told CNBC's "Futures Now" last week. "That divergence can't continue."
Glazer, who has almost $3 billion in assets under management, referred to Amazon, Microsoft, Apple, Netflix, Facebook, Alphabet, Mastercard, Visa, Adobe and Nvidia as some of the biggest names behind this year's index imbalances.
These so-called FANG [Facebook, Amazon, Netflix, Google] stocks are "not the U.S. economy," he added. "Investors need to make that distinction. They don't want to hear it."