Wall Street's biggest bull held on to his 2,300 target for the S&P 500, despite a heavy selloff and high volatility in recent days.

Stifel Nicolaus Chief Equity Strategist Barry Bannister, who went from being a bear to issuing the highest outlook for stocks, acknowledged the recent declines in the market.

"We went into the year with an 1,850 view, and here we are. We're at 1,850. So, we probably should've stopped with that," he said. "We jumped the gun, but it doesn't change the fact that things look very bullish. I expect a strong November/December rally and gains into 2015."

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On CNBC's "Halftime Report," Bannister said the stock market from November to May—"historically, and especially in midterm years"—was 30 times more rewarding than from May to October.

"On a fundamental basis, I think EPS growth slows next year," he said.

But, Bannister added, positive factors included low interest rates, reasonable stock valuations and "a bullish policy backstop."

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"Obviously 450 points in 50 trading days is a little bit of a reach, but I think we will hit the 2,300 in a reasonable time frame," he said. "We've all been shaken up, but we all know the risks."

Bannister said the market was worried about deflation, lowered 2015 global GDP and earnings and "overdue" volatility movement.

If not by year end, Bannister's 2,300 price target for the S&P 500 should come soon afterward, he added.

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"When you call me back in November/December, we'll watch that momentum rally and get a better gauge on 2015," he said. "Hopefully, by then we'll be talking about the next year, and I'm very bullish as you go out in the next six to 12 months, yes."