Investors shouldn't worry about the Dow dropping 135 points Thursday—the biggest drop since early November—because the first trading day following a great year remains a "coin toss," Sam Stovall of S&P Capital IQ told CNBC on Friday.
Stovall, S&P Capital's chief equity strategist, said that dating back to 1929, half of the first trading sessions posted losses following years in which the market gained more than 20 percent.
"So you shouldn't look to much into the first-day trading," Stovall said on "Squawk on the Street." "Being a student of history, my feeling is you look to history as a guide. Obviously it's never gospel, but you don't look to one day alone. … There's still a good chance that we have a good year, not a great year."
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The cause behind Thursday's selloff could have been retail investors realigning their portfolios after a strong year, Stovall said.
"That probably happened yesterday," he said. "You had a lot of investors who on Dec. 31 rebalanced their 401(k)s, and their managers had to put those trades to work on the first trading day."
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Stovall said he'll look toward the upcoming earnings season for guidance. He expects most of the 's industry sectors to post year-over-year gains, adding that the only laggards are likely to be utility and energy stocks.
—By CNBC's Jeff Morganteen. Follow him on Twitter at @jmorganteen and get the latest stories from "Squawk on the Street."
