Offer your thoughts or opinion on the input financial query or topic using your financial background.

Are stock index fund likely to keep being a reliable long-term investment option?
Stock index funds are likely, but not certainly, to be a good long-term investment.  In countries other than the USA, there have been 30+ year periods where stocks either underperformed compared to bonds, or even lost value in absolute terms.  This suggests that it may be an overgeneralization to assume that they always do well in the long term.  Furthermore, it may suggest that they are persistently overvalued for the risk, and perhaps due for a long-term correction.  (If everybody assumes they're safe, the equity risk premium is likely to be eaten up.) Putting all of your money into them would, for most people, be taking an unnecessary risk.  You should cover some other asset classes too.  If stocks do very well, a portfolio with some allocation to more stable assets will still do fairly well.  If they crash, a portfolio with less risky assets will have a better chance of being at least adequate.