Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

What's the average rate of return for some of the most mainstream index funds?
When asking about rate of return it is imperative to specify the time period. Average over all time? Average over the last 10 years? I've heard a good rule of thumb is 8-10% on average for all stocks over all time. That may be overstated now given the current economic climate. You can also look up fund sheets/fact sheets for major index funds. Just Google "SPY fund sheet" or "SPY fact sheet". It will tell you the annualized % return over a few different periods.