The most bullish chart in the world has a big stock market crash in the middle of it

Global markets continue to get rocked. Closing at 1,893 on Monday, the S&P 500 fell 3.9% in one day. And it's now down 11.3% from its all-time high of 2,134, which it set on May 20.

So, is it time for investor to panic, dump everything, and head for the hills?

BMO Capital's Brian Belski doesn't think so.

"We remain steadfast with our call that US stocks are six years into a 15-20 year bull market," Belski wrote in a note to clients on Monday. He's previously said that we could look forward to 8-10% average annual returns for the next three to five years.

Belski is a member of a camp of bulls who believe we are in the midst of a very long-term, secular bull market. Other Wall Street pros pushing this thesis include RBC Capital's Jonathan Golub, Morgan Stanley's Adam Parker, FundStrat's Tom Lee, and Schwab's Liz Ann Sonders.

For folks like Belski, big sell-offs, corrections, and even crashes are just part of the long-term bullish story.

"We believe the recent pullback in US stocks is very normal, healthy, and overdue," he said. "Corrections are normal and needed - and the current price weakness is serving an overdone purpose."

Check out this chart of the current cycle (dotted red line) overlaid with the average trajectories of the last two secular bull markets (solid blue line). Note the big dip in the blue line after year five. That's Oct. 19, 1987, the day the Dow plunged a breathtaking 22% in one day.

BMO Capital Markets

"Every bull market encounters several periods of market weakness, but this is something that we view as a healthy market characteristic and would encourage investors with longer investment horizons to use such periods as opportunities," Belski wrote.

While the risk of a much scarier crash is very real, history shows that it pays to be patient during times like this.