The recent plunge in momentum stocks has some worried, but Ed Yardeni of Yardeni Research says that it may actually be a good sign.

“We believe that the recent meltdown in the ‘momentum’ stocks, the ones that had been soaring over the past couple of years to excessively high valuations, reduces the risks of a broader melt-up followed by a more severe meltdown,” Yardeni tells USA Today (via CNBC). “If so, then it’s actually a positive development for the longevity of the secular (multi-year) bull market.”

Yardeni said earlier this year that emerging market concern-fueled declines represented a good buying opportunity; last summer he said he thought the bull market had another couple years to run.