Among the equity market themes one learns early on is that market history is not prologue: past performance is not indicative of the future. We learn, too that market performance is not always positive. Another important premise is that diversification is your friend. These themes apply to the relative performance of the groups of stocks we tend to emphasize in our portfolios. Their long-term relative performances resemble, but generally are not exactly like, those seen in history. While long-term positive, they are not always so. And including a range of factors in the portfolio may lead to better outcomes over time.