Lately there has been a rash of news articles and TV interviews touting the outsized returns earned by endowment funds and so-called sovereign wealth funds, which are pools of capital that state or national treasuries set aside for investment. These commentators like to tell us we too can invest like Yale University or Norway.Well I don't think we can invest exactly the way endowments do, but we can put our money to work in similar ideas and themes. The big "macro" behind these funds is that they diversify across many types of assets such as private equity, commodities and various hedge fund strategies -- not just stocks, bond and cash. And it's true that there are stocks, exchange-traded funds and other kinds of securities that provide access to similar, if not necessarily identical, asset classes. Selecting a couple of these themes and adding them to your portfolio can improve your diversification and boost your returns. The reason I say we cannot invest exactly like endowments and sovereign wealth funds is that there is no perfect substitute for some of the things they buy, and they're simply not available to small investors. For example, Jack Meyer, the former boss at the Harvard Management Company, is well known for getting exposure to timber by buying timberland in New Zealand.