Surging consumer sentiment in January will provide bullish support for stocks for the rest of the year.

That’s the implication of a study published several years ago in the International Review of Financial Analysis. The correlation exists because of when investors typically alter the equity allocations of their monthly 401(k) contributions — that is, how much of their monthly payroll deductions go into stocks as opposed to other asset classes. Though investors can alter that equity allocation at any time, most typically…