If I use a flexible portfolio, could my performance change?

Adjusting an investment portfolio requires careful consideration and experience. The allocation you choose is your responsibility, and your performance may be better or worse than the performance of one of Betterment’s own portfolio strategies with a comparable level of risk.

Additionally, although Tax Loss Harvesting+ and Tax Coordination will still work, altering or removing asset classes may impact the effectiveness of these strategies relative to their effectiveness when used with the Betterment Portfolio Strategy.