Factor-based investing spreads from stocks to bonds

COMPARED with equity investing, bond investing can seem stuck in the dark ages. As hedge funds and asset managers use whizzy algorithms to trade shares automatically, bond-fund managers still often call traders by phone. So when new investing strategies do arise, they make an even bigger splash. “Factor” investing is the latest example.

This is the idea, credited to economists Eugene Fama and Kenneth French, that predictable, persistent factors explain long-term asset returns. Their 1992 model for equities used the size of firms and what became known as “value” (the tendency for cheap assets to outperform pricey ones). Later models added factors such as “momentum” (the tendency of prices to keep moving in the same direction). Factor-based analysis has squeezed active managers (since it explains much of their returns) and helped drive the rise of passive investing. Investors can access factors in equities, often called “smart beta”, through cheap index-tracking funds or exchange-...