jensen’s alpha

Think of a driver who boasts he got from Ikeja to Victoria Island in twenty minutes. If he did it at two in the morning on an empty road, it is nothing special. If he did it by driving against traffic on the third mainland bridge, he was merely reckless. But if he found sensible back streets during peak evening rush hour, that is genuine skill.

Jensen's Alpha is the financial world's way of checking that driver's dashboard.

When a fund manager in Lagos tells you their portfolio gained twenty five percent this year, you cannot celebrate yet. If the wider Nigerian stock exchange jumped thirty percent, or if safe treasury bills were already paying twenty percent, your manager actually underperformed the risk they asked you to take.

This measure was created by an economist named Michael Jensen. It looks at the return you should have earned, based on how jumpy the market was, and compares it to what you actually pocketed.

A London fund manager handling diaspora savings might claim genius by buying volatile tech shares during a global boom. Jensen's Alpha strips away the tailwind of the market. It asks whether that extra profit came from deep homework or just blind luck in a rising tide.

If the final number is positive, your manager added true value above their benchmark. If it sits at zero or turns negative, you are paying heavy management fees to someone who merely drifted along with the current.