When we first exposed the shockingly dire lack of breadth in US equity markets, it was shrugged off by the mainstream media as yet another ‘worry’ in the wall to climb. It seems, however, that facts inevitably force their way to the surface and so both Bloomberg (more than 100% of this year’s increase in the S&P 500 Index is attributable to two sectors, health-care and retail. That’s the tightest clustering for an advancing year since at least 2000) and The Wall Street Journal (Amazon, Google, Apple, Facebook, Gilead and Walt Disney Co. account for more than all of the $199 billion in market-capitalization gains in the S&P 500) have been forced to expose the ugly truth about US equities… it is not a stock market – it’s a market of 6 tail-chasing momentum stocks.

U.S. equities are being pushed along by the fewest stocks in more than 15 years, which as Bloomberg  is a sign of fatigue in a bull market that already rivals anything since World War II in duration.

More than 100 percent of this year’s increase in the Standard & Poor’s 500 Index is attributable to two sectors, health-care and retail. That’s the tightest clustering for an advancing year since at least 2000, data compiled by Bloomberg show.

Breadth has fallen apart in a rally that is now the third longest since 1940, leaving investors exposed after three years without a 10 percent correction. Adding to concerns: the two industries shouldering this year’s advance trade at more than 22 times annual earnings — a 20 percent premium to everything else.

“You’ve gone from a market which lives or dies by people’s feelings about the macro environment to a market that’s going to live or die according to the bottom-up beliefs of the prospect of a limited number of individual issues,” said Michael Shaoul, chief executive officer at New York-based Marketfield Asset Management, which oversees $5 billion.

Reliance on fewer and fewer companies has been a hallmark of maturing bull markets, most memorably the Internet bubble when six computer and software companies accounted for 55 percent of the S&P 500’s gain over the 12 months leading up to the peak.