The stock market soared last year, despite decelerating earnings growth, but profit performance will have to improve this year for stocks to continue the rally, experts say.

"If the market's going to have another leg up here, it's really going to have to be driven by earnings growth," Jim McDonald, chief investment strategist at Northern Trust, tells The Wall Street Journal. "Earnings have turned from being a secondary issue to being the primary issue."

Analysts expect companies in the Standard & Poor's 500 Index to produce a 6.1 percent increase in fourth-quarter profits per share, up from 4 percent in the third quarter, according to FactSet, The Journal reports. That would constitute the strongest three-month period since the fourth quarter of 2012.

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But even if that forecast is met, 2013 would represent the third straight year of slowing profit growth. Analysts predict earnings per share will increase 5.6 percent for all of last year, down from 6 percent in 2012.

For this year, analysts' now call for profit gains of 10 percent, but early optimistic forecasts are often revised downward later.

"We'll have modest but satisfactory, sustainable improvement in growth," Margie Patel, a senior portfolio manager for Wells Capital Management, tells The Journal.

When it comes to retailers, their profit pictures aren't so pretty for the fourth quarter. Seven major retailers have cut their earnings forecasts for the period, The Associated Press reports.

"This was a holiday season that most stores would like to forget," Ken Perkins, president of RetailMetrics research firm, tells the AP.

Editor’s Note: 5 Shocking Reasons the Dow Will Hit 60,000

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