Anyone shorting the global stock market stands to make a "fool" of themselves as equities continue to rally, Dennis Gartman, the founder and editor of the "Gartman Letter," told CNBC on Friday.
The tech-heavy Nasdaq Composite rallied to a record high on Thursday, helped by upbeat earnings. The broader S&P 500 stock index meanwhile has been on a broad upward trend since mid-2011 and is up 2.5 percent year-to-date.
"It's still a bull market…and if you try to sell it, if you get out of it, especially if you try to go short of it, you make a fool of yourself," Gartman said in a TV interview.
Analysts have raised concerns about the hefty valuations of stocks.
The S&P 500 is currently trading 16.5 times forward estimates of its companies' earnings, according to recent data from Reuters. Forward estimates are an important metric that many analysts use to gauge the attractiveness of equity indexes. The S&P 500 is about 10 percent more expensive than its historic average of 15, according Reuters estimates.
"What I find interesting and relatively amusing is that every smart guy and every smart woman I know…keeps trying to sell it short, and they put forth wonderful ideas about why stocks are overvalued… but the stock market keeps moving higher," Gartman said.