Diversification does not assure a profit, nor does it protect against a loss in a declining market.
The S&P 500 or Standard & Poor's 500 Index is a market-capitalization-weighted index of the 500 largest U.S. publicly traded companies.
The S&P 600 is an index of small-cap stocks managed by Standard and Poor's. It tracks a broad range of small-sized companies that meet specific liquidity and stability requirements.
The Russell 2000 Index is a small-cap stock market index that makes up the smallest 2,000 stocks in the Russell 3000 Index. The index is maintained by FTSE Russell.
The "markets" referred to is the S&P 500 index.
The S&P 500 is a market-capitalization-weighted index of the 500 largest U.S. publicly traded companies.
The "commodity index" referred to is the Bloomberg Commodity Index.
The Bloomberg Commodity Index is a broadly diversified commodity price index and tracks prices of futures contracts on physical commodities on the commodity markets.
The "Real Estate Investment Trusts" referred to is the Nareit All Equity REITs Index.
The FTSE Nareit All Equity REITs Index is a free-float adjusted, market capitalization-weighted index of U.S. equity REITs (Real Estate Investment Trusts).
Indexes are unmanaged, do not incur fees, and it is not possible to invest directly in an index.