CFRA's Sam Stovall sees stocks hitting all-time highs before April ends.
However, that's where his bullish case takes a bearish turn. Stovall warns a "sell in May and go away" phenomenon is unfolding.
"The market could end up attempting to digest some of the gains that it's already experienced," the firm's chief investment strategist said Tuesday on CNBC's "Futures Now. "
He's building much of his case on a historical trend dating to World War II.
Stovall notes that 2019 is on target to be the fifth best year-to-date performance through April since the war. But his trend also implies stocks will falter in between May and October. He calculates stocks recorded an average price gain of 0.05%.
"Half of the time the market was lower in that six month period," said Stovall.
If you zoom in on May alone, the data is even worse. He finds stocks were up just 0.01% of the time.
To position for a tougher month, Stovall is advising investors with shorter-term horizons to begin rotating into defensive groups.
He sees positive momentum returning to the market by year-end.
"The strength in the market early in the year combined with what normally happens after a very strong beginning to the year implied that we will be up for the year," Stovall said. "We'll be good in November and December."
His year-end target is 2,975, just 1 percentage point over all-time highs.