New evidence has emerged in support of an old stock-picking saw. Earlier this week, Chip Dickson, portfolio strategist at Lehman Brothers, issued a report boosting the Wall Street adage that "As January goes, so goes the year."

Dickson found that, since 1970, the S&P 500 has continued higher throughout the year 86% of the time after rising in January compared with 57% of the time when it fell in the first month of the year. On average, the S&P 500 returned 13.3% in the year following its five best January performances since 1970 versus only 4.2% following the worst five Januarys.

According to Dickson, investors can maximize returns simply by adding January's best stock-market performers to their portfolio while sloughing the laggards. "Portfolio performance for a calendar year can often be improved by simply selling the worst performers at the end of January," wrote Dickson in the report.

In fact, selling poorly performing stocks might be the best move investors can make. According to Dickson's numbers, the stocks that performed worst during the first month of the year have typically continued their slumps during the following 11 months. Since 1970, January's laggards have returned only 4% from February through December versus almost 10% for the top performers.

In past years, the best-performing stocks of January have been household and personal-products companies, software developers and retailers of food and consumer staples. Dickson said January's laggards have historically been transportation companies, health-care providers and commercial service businesses.