This portfolio has about 21+ year back testing history. 

Inception date: 6/28/1991. 

This portfolio tries to use the funds with longest price history. The international and emerging market and REITs are the ones with shorter history.

Funds used in this portfolio:

• U.S. stocks: Vanguard 500 Index (VFINX), inception:3/27/1987
• European stocks: Vanguard European (VEURX), inception: 11/1/1990
• Pacific stocks: Vanguard Pacific (VPACX), inception: 11/1/1990
• US REITs: Vanguard REITs (VGSIX), inception: 6/28/1996
• Gold: GLD, inception:1/4/1971. Before ETF GLD’s inception on 11/18/2004, we use London spot gold price (monthly closing). 
• US Bonds: Vanguard Total Bond Index (VBMFX), inception: 6/4/1990
• CASH: calculated using 3 month T-Bill interest. 

This portfolio has the following important characteristics: 

• It uses index mutual funds only.
• It does not have survivability issue that has been cited as one of the biggest issues in many back testing studies.
• It does not have slippage or trading friction issue as mutual funds are only traded at the closing price.
• It has the longest history for public mutual fund or ETF based portfolios. As the moment, it has more than 21 years back testing history.
• It uses geographical diversification among stocks. The reason to do so has more to do with the longevity of mutual funds: Vanguard European and Pacific stock funds have much longer history than Vanguard Total International Stock Market fund or Vanguard Emerging Market Stock Fund. This is the main difference from Six Core Asset ETFs.