Want to know how well your company’s doing? Take a look at your boss’s signature.

That’s the gist of a new study from the University of North Carolina, which analyzed the signatures of more than 600 CEOs, from some of the world’s biggest companies. Researchers say it’s the first study to show a link between the size of a boss’s signature, and their performance. And in general, the bigger the signature, the more likely your boss is to overspend, make poor decision, and run your company into the ground!

For example: The biggest signature this study measured came from Timothy Koogle, the former CEO of Yahoo. He was paid a huge salary, and made poor financial decisions for the company – which fits this model to a T.

Because CEOs with bigger signatures tend to get the highest salaries, regardless of their performance. The leading theory is that people with big egos are usually better at intimidating others, and “sweet-talking” themselves into bigger paychecks at work.

Sean Wang is a business school professor, and he says many psychological studies show that a bigger signature tends to mean a bigger ego. It’s also the sign of a narcissist, who values their own opinions more than others.

And Wang says narcissism is the last thing you want from the person running your company, because good bosses are supposed to encourage workers, and bring out their best. But narcissists tend to dismiss, belittle, or even ignore the abilities of others! And that’s what makes them such bad decision makers.