Louise Yamada has a strong message for investors: Don't get complacent.
The markets have been in rally mode since the start of the fourth quarter, with the S&P 500 and Dow Jones industrial average each surging more than 5 percent. Both indices are trading at levels not seen since late August. But according to Yamada, any strength should be used as an opportunity to sell.
"You always get a rally after a big decline," the renowned technician told CNBC's "Futures Now" on Thursday. "The point is that we initiated a downtrend in August and once a downtrend is initiated after something that looks like a larger top, these rallies tend to go back into resistance." Yamada identified the next levels of resistance as the falling 200-day moving average, which comes in at around 2,050 to 2,060.