If your portfolio contains an asset with short history, you can still backtest the portfolio for extended periods of time by using backfills. Based on feedback from advisors, the latest release of Portfolio Lab adds enhancements to this functionality.

Choose any asset for backfill

You can choose any stock, mutual fund, ETF or index to act as the backfill (in the previous version, only certain indexes could be used.) The following example shows two backfills, one using a fund and the other one using an index. The backfill portions are shown in blue:


VWNEX (Vanguard Windsor fund Admiral shares) has history only from 2001. To allow backtest before 2001, the history is backfilled with VWNDX (Vanguard Windsor fund Investor shares.) Similarly, IVV ETF price history is backfilled using the S&P500 index Total Return.

Double backfill

The asset you choose as a backfill may itself not have enough history to extend to the desired period length. In this case, Portfolio Lab uses a second backfill.


In the example above, SPVIX (a small-cap mutual fund) has history from 2002. For backfill, SPVAX (the same fund but with a different share class) is used from 1997 to 2002 and the S&P 600 SmallCap Index is used as a second backfill from 1994 to 1997.