The S&P 500 has closed below its 200-day moving average, currently around 1,905, marking the end of nearly two years trading above that technical indicator.
"You have to go back to the late '90s to find another streak of success like," said Rich Ross, global technical strategist at Auerbach Grayson, who also noted the last time the market broke such a long streak inthe200-day moving average, the S&P 500 went on to lose 22 percent.
Though the index is down 7.2 percent from its Sept.19 all-time high of 2,019.26, Ross doesn't believe the S&P 500 will see a drop such as the one back in 2000. Nonetheless, he sees more downside ahead from current levels of 1,879.92.
"When you look longer term, that's where you really start to worry about the downside when you break below that key 1,900 level," said Ross, a "Talking Numbers" contributor. "If you break below there, the next real support could come in around the 100-week moving average. That's in at around 1,740. That's another 9 percent down from here and that also coincides roughly with the lows of 2014, which we established in February."
The fundamentals also are negative for the S&P 500 index, according to Gina Sanchez, founder of Chantico Global. She sees the index as still being overvalued despite its decline. However, she doesn't believe the S&P 500's main problem is its price-to- earnings multiple (now around 16 times) but because of the quality of the earnings on which the valuation metric is based.
"They've been coming from unsustainable sources and that has to change," Sanchez said of earnings. "The market has to come back to a price that makes sense."
Questions about global growth – particularly with Europe – and the stronger will hit the S&P 500, said Sanchez, a CNBC contributor
"Even though we are having this slow recovery [and] we are seeing decent earnings," she said, "I think that there's still too much in the price right now. That has to be taken out. So I'm expecting far lower than this."
To see the full discussion on the S&P, with Ross on the technicals and Sanchez on the fundamentals, watch the above video.