Realty Income Corp. will be added to the S&P 500 index after the close of trading on April 6, the Escondido-based company announced.

It will be the third San Diego County-based company to join the index of large-capitalization U.S. equities, after Sempra Energy and Qualcomm Inc. It will also be one of 24 real estate investment trusts included in the index, which is owned and tracked by the financial services firm Standard & Poor’s Financial Services LLC.

According to Standard & Poor’s, Realty Income as of March 30 had a market capitalization of approximately $11.59 billion.

“The addition of our company to the S&P 500 index is a milestone that recognizes our proven track record of performance throughout our long operating history,” said Realty Income CEO John P. Case, in a statement. “We are pleased by this achievement and remain committed to operating our company in a manner that supports the payment of growing monthly dividends over time.”

Realty Income (NYSE: O) was founded in 1969 and has been traded publicly since 1994. Officials said the company to date has declared 537 consecutive common stock dividends in its operating history and increased the dividend 80 times since its public listing.

The company owns more than 4,300 commercial properties nationwide, including retail, industrial and related buildings.