Although still awaiting a formal announcement by S&P, the inclusion would take effect sometime this month.   The move comes only two years after S&P began including some REITs in its 500-stock index as Wall Street is increasingly warming up to the sector that has had an average 7% yield over the past three years, according to a Wall Street Journal report.

Raymond Mathis, REIT equity analyst at S&P told the Wall Street Journal the decision to include REITs was spurred, in part, by the amount of phone calls he said S&P fielded from institutional investors who wanted to invest in REITs. The reason for the demand are some institutional requirements of a high S&P quality ranking.   In general, the rankings, graded on a scale of A-plus to C, with A-plus signifying the company has the strongest dividend and earnings growth, appear on the front of S&P’s stock reports, which are available to individual and institutional investors, mutual funds, and financial advisers who subscribe to S&P.

The rankings are calculated annually. But they can change before a year ends if there’s a major dividend cut, or bankruptcy in the interim.   However, the rankings are less a predictor of future performance than a look at how companies perform over time, based on the system’s approach of appraising the growth and stability of earnings and dividends on individual companies, based on per-share earnings and dividend records over the past 10 years.

Thus far, the only REITs assigned A-plus ratings are shopping-center ownersKimco RealtyCorp. andMid-Atlantic Realty Trust, of Lutherville, Md.   To see the complete rankings for REITs, investors can visit  www.standardandpoors.com  and click on “Equity.”