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

Is investing exlusively in a small-cap index fund a wise investment?
Stock portfolios have diversifiable risk and undiversifiable risk.  The market rewards investors for taking undiversifiable risk (e.g. owning an index of oil producing companies) and does not reward investors for assuming diversifiable risk (e.g. owning a single oil producing company).  The market will not provide investors with any extra return for owning a single oil company when they can buy an oil index fund at no additional cost. Similarly, the market will not reward you for owning a small-cap index fund when you can purchase a globally diversified / capitalization diversified index fund at no additional cost.  This article provides a more detailed description. The Vanguard Total World Stock Index Fund is a much better staring point for an equity portfolio. You will need to make sure that the asset allocation of your overall portfolio (e.g. stocks, bonds, P2P lending, cash) is consistent with your time horizon (5-10 years).