In a rare reorganization, S&P index organizers are separating real estate investment trusts from the rest of the financial sector, bringing the number of major industries in the index to 11.

That means ETFs tracking the index’s financial sector, or that represent all sectors, may have to re-balance.

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The new sector will be called Equity Real Estate Investment Trusts. It excludes mortgages REITs, which will still be under Financial sector, under a new category of its own.

The change comes as S&P Dow Jones Indices and MSCI revise the Global Industry Classification Standard (GICS) — the framework for industry and sector weightings in indexes.

It’s the first time a new sector has been added to the GICS since it was founded in 1999.

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“The creation of an eleventh sector recognizes the growing importance of real estate in the world’s equity markets,” says David Blitzer, managing director and chair of the index committee at S&P Dow Jones, in a release.

The organizers say the change “reflects the position of real estate as a distinct asset class and a foundational building block of a modern portfolio, rather than an alternative.”

As of today, the new sector is officially part of the GICS, but it won’t be reflected in any S&P indices until September 16, the same day as the indexes are rebalanced.

Under the new structures, the GICS will have 11 sectors, 24 industry groups, 68 industries and 157 sub-industries.

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About US$68 billion in fund investments already track REITs, Bloomberg reports.

There are currently 28 REITs in the S&P 500, with more than US$580 billion in market capitalization — larger than the telecommunications and mining sectors.

More industry changes

Copper will get its own sub-industry under the Metals and Mining Industry. It was formerly in the Diversified Metals and Minerals sub-industry.

The Catalog Retail sub-industry is being closed, and its companies are being reassigned into the Internet Retail sub-industry. That category will now be called Internet and Direct Marketing Retail, and will hold companies that reach customers mainly through internet, mail order or TV home shopping.

There is a new sub-industry for Financial Exchanges and Data. Companies in the new sub-industry used to fall under the Specialized Finance sub-industry. The new category will be under the Capital Markets Industry sub-industry, which is a part of the Financial Sector. Companies like MSCI (which co-manages the GICS) will fall under the new Financial Exchanges and Data category.