Investors should be cautious despite the big rally on Wall Street on Tuesday, warned Jim Cramer of CNBC.
The market wanders through a volatile time and Mark Sebastian, who calls the "Mad Money" host named "VIX master" is vigilant. The VIX or CBOE Volatility Index measures market risk based on investor sentiment about equities listed in the S & P 500.
Cramer studied Sebastian's analysis to get an overview of the market situation.
"Although he does not predict a major decline, he says you should prepare for troubled waters and perhaps a modest retreat," Cramer said. "The averages have not really digested these recent gains, and as we saw last week, big gains can lead to serious stock market rebound."
The VIX, called the "fear scale," and S & P 500 indexes usually run in opposite directions, Cramer explained. If they reflect, this is more of a warning sign.
After a series of turbulent trading days, US averages rose on Tuesday and the VIX slid to around 1
"Although we had a lot of turbulence, Sebastian was worried that the volatility index seems to sneak up with the stock market," said Cramer. In recent years, "every time S & Ps had a fast rally that did not really bring the VIX to a standstill … led to a sort of sell-off … The most notable was the big outbreak in January 2018."  Sebastian, a technical analyst and founder of OptionPit.com, believes the VIX will flash a yellow light as long as the index stays above 16. The Chartist warns that the uptrend is more limited than most expected, Cramer said.
"He says the market needs to retreat for a few days, then we hope to achieve a slower, more logical rally," Cramer continued. "Until we digest these recent gains, Sebastian predicts the fear indicator will stay above 16 and this market slips."