NEW YORK (MarketWatch) — Long-term investors are getting a rare signal suggesting that now might be a great time to buy stocks — that is, if they are willing to risk a potential rough patch in the near term.

For just the fourth time in over 50 years, the S&P 500’s dividend yield moved last week above the yield on the benchmark 10-year Treasury note. If history is any guide, this means 2015 could be a very good year for the stock market.