Indexing sounds like an easy way to track the market's performance, but if your indexed assets are held in financial advisors' accounts, it can come with a big cost: significant underperformance. Over 20 years, we estimate in this hypothetical example that the cumulative cost as a result of a 1% annual financial advisor fee on indexed assets can amount to as much as 66% of a saver's initial investment -- just for holding an index fund. Please be careful out there!