Share your insights or perspective on the financial matter presented in the input.

Is investing exlusively in a small-cap index fund a wise investment?
If the OP is saving 33% if his/her current income, he/she doesn't want or need yet more income from investments right now. The advice on "diversifying" in the other answers is the standard "investment advisor" response to beginner's questions, and has two advantages for the advisor: (1) they won't get sued for giving bad advice and (2) they can make a nice fat commission selling you some very-average-performance products (and note they are selling you "investment industry products," not necessarily "good investment opportunities" - advisors get paid commission and bonuses for selling more stuff, not for selling good stuff).  My advice would be to drip-feed some of your excess income into the emerging market sector (maybe 1/3 or 1/4 of the excess), with the intention of leaving it there untouched for up to 20 or 30 years, if need be. At some unknown future time, it is almost certain there will be another EM "boom," if only because people have short memories. When that happens, sell up, take your profits, and do something less risky with them.  You might consider putting another slice of your excess income into the commodities sector. I don't know when the oil price will be back at $150 or $200 a barrel, but I would be happy to bet it will happen sometime in the OP's lifetime... Since you apparently have plenty of income and are relatively young, that is the ideal time to adopt a risky investment strategy. Even if you lose your entire investment over the next 5 years, you still have another 20 years to recover from that disaster. If you were starting to invest at age 56 rather than 26, the risk/reward situation would be very different, of course.