According to the Lindsey Group's Peter Boockvar, bullish sentiment is at levels even higher than they were in December 2013, October 2007and August 1987, and we all know how that ended.
Using data from a survey conducted by Investors Intelligence, Boockvar says the number of bulls exceeds the number of bears by a near record margin.
"Bulls are now just .3 [points] from a record high in December '04 and compares with 61.6 in December '13, 62.0 in October '07 and 60.8 in August '87," Boockvar wrote in a morning note.
Fellow technician, Richard Ross, global technical strategist at Auerbach Grayson, agrees with Boockvar's assessment.
"Market sentiment really is in the bailiwick of the technician," said Ross, a "Talking Numbers" contributor. "I love to use sentiment indicators. But, let's remember they're not the greatest market timing tool. It's not the proverbial bell that rings at the top. It's more like a ticking time bomb."
Ross thinks investors should be on guard whenever bullish sentiment exceeds 55 percent. But, for the short-term, the chart of the S&P 500 doesn't point to a serious decline.
"This is not the most nefarious short-term chart," Ross said. He sees the S&P 500 as trading in a well-defined trend channel for the past 12 months, with a "support zone" in the 1,850 to 1,900 range. "That's going to be a zone of support on any pullback," he said. "You don't want to be overly bearish unless you breach back below that, which I do think, ultimately, will happen."
It's in the long-term chart "where the magic happens," Ross said. He sees significance in the S&P 500's 150-week moving average. "It provided a great tell for the market," he explains.
Key is the technical symmetry of the period from 2003 to 2008 and 2010 to 2014. The index broke above the 150-week moving average in 2003, peaked 47 months later, and subsequently collapsed during the financial crisis. It has now been 45 months since the index broke above the 150-week moving average again in 2010. For Ross, that's a good enough reason to sell.
"The timing is right," Ross said. "The sentiment is elevated. You want to leave this party while you're still having fun, as hard as it may be to do."
Gina Sanchez, founder of Chantico Global, is also bearish on stocks but thinks low interest rates will keep the market steady, if just for the time being.
"I'm not a big fan of stocks, particularly at these prices," said Sanchez, a CNBC contributor. "The market is well ahead of itself. So, you can count me in the bear camp. However, as long as interest rates stay low and somewhat benign, that's really what's been keeping stocks where they are."
Sanchez thinks rates will have to move higher to cause the market to tumble. "The fundamentals just don't support valuations where they are," she said. "I'm not sure what it is that kicks the legs out from under this market, but something is coming. It's hard to call the timing on it. But, what I can say is this isn't a value here."
To see the full discussion on the S&P 500, with Ross on the technicals and Sanchez on the fundamentals, watch the above video.