On our site, every return comes with a companion figure. You'll see something like +1.8% · SPY +0.9% · α +0.9%. The first number is what a portfolio actually did. The second is what the market did. And that third one — the α — is the number we care about most. So what is it?
Alpha is the part of a return that the market doesn't explain. When stocks broadly rise, almost everyone's portfolio rises with them — that's not skill, that's the tide. Alpha asks a sharper question: once you subtract the tide, is anything left over? If the market is up 10% and a portfolio is up 12%, roughly ten of those points came from simply being invested, and the extra two points are where skill — or luck — might be hiding. That leftover is alpha.
It helps to name alpha's quieter twin: beta. Beta is the market-riding part — the return you get just for showing up and holding stocks. A rising tide lifts all boats, and beta is the tide. Alpha is how well you actually sailed. Most of any given year's return, for most investors, is beta. That's not an insult; it's just arithmetic. The whole game of active investing is trying to add a little alpha on top without taking wild risks to get it.
How is it measured? The crude version is simple subtraction: your return minus the benchmark's return over the same window — that's the α we display next to SPY. A more formal version, called Jensen's alpha, first adjusts for how much market risk you took on (your beta) before deciding what's genuinely "excess." Either way, the spirit is identical: strip out the market, and see what remains.
A little history worth knowing. The term comes from economist Michael Jensen, who in a 1968 study of mutual funds ("The Performance of Mutual Funds in the Period 1945–1964") built the first rigorous measure of manager skill above the market. His conclusion was famously humbling: on average, the funds he studied could not pick well enough to beat a simple buy-and-hold of the market after costs. That result helped launch the index-fund era — and it's exactly why alpha deserves respect. Positive, durable alpha is genuinely hard. Anyone who treats it as easy is usually measuring luck.
Which is the catch to watch for. Over a few days or even a few weeks, alpha is mostly noise — a lucky pick or a single good session can produce a big number that means nothing. Real alpha only shows up over enough time for luck to average out. So a short streak of beating the market is not proof of skill; it's a hypothesis waiting for more data. Honest scorekeeping means resisting the urge to celebrate a good week as if it settled the question.
Why we lead with alpha. An absolute return, on its own, is easy to misread. "Up 8% this month" sounds great — until you learn the market was up 9%, which means the portfolio quietly lost ground versus just buying the index. Alpha is the number that keeps everyone honest: it asks not "did you make money?" but "did you actually add anything the market wasn't already handing out?" That's the harder question, so it's the one we put front and center — and the one we publish, day after day, wins and misses alike, so it can be judged over time rather than taken on faith.
This is informational and entertainment content — not investment advice. Figures are illustrative and past results do not guarantee future outcomes.