In the six decade-history of modern finance, the basic lesson is that risk matters. Managing risk, in other words, is more productive than chasing return. But what exactly is risk? Alas, there are no easy answers, but at least there’s a beginning.
Financial economics has been uncovering what risk means for decades, refining our understanding of financial hazard and, more importantly, how it’s priced and what it all implies for portfolio design. At the basic level, market risk—beta—is the elephant in the room. Unless you’re willing to hold extreme portfolios—a handful of securities, for instance—beta will cast a long shadow over risk and return.