The REIT companies have an umbrella organization called NAREIT – The National Association of Real Estate Investment Trusts.

NAREIT developed a number of REIT indices whose purpose is to show changes in shares prices of REITs that are traded in American exchanges.  These are the five popular indices.

1.  NAREIT All REITs Index
   This index includes all of the REITs traded in American exchanges.

   The market cap of all of the REITs in this index is 190 billion dollars (early 2003).

2. NAREIT Real Estate 50 Index
   This index includes the fifty REITs with the largest market caps.

   The trusts included in this index have a market cap of 140 billion dollars (early 2003).

3. NAREIT Equity REIT Index
   This index is made up of 146 REITs that specialize in purchasing income-producing real estate. These REITs have a market cap of 175 billion dollars (early 2003).
4. NAREIT Mortgage REIT Index
   This index only includes 20 REITs that specialize in purchasing mortgages.

   The total market cap of the trusts in this index reaches 10 billion dollars (early 2003).

5. NAREIT Hybrid REIT Index
   This index includes the shares of 7 mixed trusts.

   Those 7 trusts have a total market cap of 4.5 billion dollars (early 2003).