What are the six tell-tale signs that you are working for a boss with an ego that casts a shadow?

What out for the prominence of the boss's photo in the annual report; his (and it usually is a male) prominence in company press releases; the length of his "Who's Who" entry; how often he uses the first person singular in interviews; and the ratios of his cash and non-cash compensation to those of the firm's second-highest paid executive.

That seems to be the findings of a new study getting a fair bit of airplay lately.

For more on the study, check out the version in The Economist.

Narcissistic bosses can be dangerous, according to the researchers, because they tend to make bigger changes in areas like spending and leverage and they carry out more and bigger mergers and acquisitions. That means their results can both more extreme, with more huge wins or terrible losses, and more volatile than those of firms run by others.

Still narcissism has its "upside". Narcissistic leaders can also be visionaries, say some experts.

Narcissism can be a tool for engaging others in their vision of the world, which can make the organisation quite exciting. And dangerous.

When that happens, it's up to the board of directors to keep the ego-maniac in line.