In this edition of The Motley Fool's "Ask a Fool" series, Motley Fool One analyst Jason Moser takes a question from a reader who asks: "I have a large investment in Disney (NYSE:DIS) and InvenSense (NYSE:INVN). Should I sell Disney at $82 and reinvest proceeds into InvenSense? If I do this I will have 2,900 shares of InvenSense hoping for a upward movement."

As a guideline, Jason believes that you don't want to overweight your portfolio in any investment. No matter how much you may like the company and its prospects, investors need to expect the unexpected, and diversity helps prepare you for just that. Because small caps are inherently riskier because of their size, investors should plan on owning a number of small caps to spread that risk out.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.