You've just been named CEO of a Fortune 500 company. Your ego fills the room. The laws of gravity don't apply to you.

And naturally, you want to make an impact. So you pour money into mergers and acquisitions, and when you're not trying to acquire another firm, you guide company resources into research and development. You're a genius, and the world will soon be clinging to your every new product.

The only problem: your company will likely underperform. Research by former Rice Business visiting professor Sean Wang (now at Cox School of Business as SMU), along with Nicholas Seybert of the University of Maryland and Charles Ham of Washington University at St. Louis, reveals the high costs of an out of control CEO ego.

The researchers' first challenge was establishing who could legitimately be called a narcissist. What does the term mean, exactly? While there are varying definitions, Wang's team focused on narcissism as a basic personality trait rather than a mental illness. As a personality trait, narcissism is associated with entitlement, vanity, authority, and a sense of superiority.

To spot narcissists, the team took a novel approach: they examined their research subjects' signatures. Signature size turns out to be a handy measure for egos, because it doesn't require participants to answer direct questions about their personalities — and because participants are unlikely to know that ego can affect something as simple as a signature.

Just having a big ego, though, does not a narcissist make. To validate a link between a person's signature and narcissism, the researchers asked 53 graduate business students to provide their signatures by signing a document, and then to take a personality survey that measured narcissism. The findings documented that indeed there was a strong correlation between signature size and narcissism.

Next, the researchers obtained data from prior psychology research on employee perceptions of 32 technology-firm CEOs. Of the 24 CEOS for whom the researchers also had signature samples, they found a significant correlation between narcissism and signature size.

Armed with these findings, Wang and his colleagues were able to extrapolate the narcissistic traits of thousands of CEOs whose signatures were readily available on proxy statements and other corporate documents. The researchers ultimately studied 741 CEOs from 411 firms during the period between 1992 and 2015, corresponding to 6,361 firm-year observations with a median of eight fiscal years per CEO.

They found a pronounced behavior pattern. Firms led by narcissistic CEOs invested more in high-exposure areas such as research and development and mergers and acquisitions, but shied away from routine capital expenditures for day-to-day productivity. This trend was even more pronounced during periods of financial slack, suggesting that narcissistic CEOs prefer an aggressive management style whenever possible. Financial productivity delivered by these narcissistic CEOs in terms of profitability was lower than their less egotistic counterparts.

The research has multiple implications. Narcissistic leaders, past research shows, are prone to make bad decisions — in part because they are bad listeners. As a result, they often dominate the decision process without incorporating feedback or ideas from others. Ironically, they mistakenly perceive this behavior as a signal of competence and strong leadership.

To counter these bad habits, the researchers say, during periods of financial sluggishness investors and corporate boards should combat excessive narcissist-led investment by pushing for higher dividend payouts. Given that narcissistic CEOs overinvest in R&D, investors also need to closely monitor whether such investments represent real innovation or just vanity. Finally, boards of directors should be aware that narcissistic leaders tend to command higher salaries — and consider whether their CEO falls into this category, and is essentially getting higher pay for inferior performance.

In short, to really be as boss as they see themselves, narcissistic corporate leaders need to recognize their tendencies and rigorously check their egos. Boards, meanwhile, should closely monitor their CEO's priorities in directing firm resources. It could be the writing on the wall.

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This article originally ran on Rice Business Wisdom.

Sean Wang is a former visiting assistant professor of accounting at Jones Graduate School of Business at Rice University. He is now an assistant professor at Cox School of Business at SMU.