Beware those toxic co-workers

Toxic coworkers are more than a workplace nuisance — they represent a substantial financial and cultural liability. A recent Harvard Business School study finds that avoiding or removing toxic employees delivers nearly twice the value of hiring a top-performing “superstar.”

Drawing on employment data from nearly 60,000 workers across 11 companies, researchers focused on the most severe forms of toxic behavior — misconduct that resulted in termination, including theft, fraud, harassment, bullying, and workplace violence. These employees were found to accelerate turnover, damage morale, and erode productivity across teams.

The economic contrast is striking. While a top 1 percent performer generates an estimated $5,303 in value through higher output, avoiding a toxic hire saves approximately $12,489 per employee — a figure that excludes potential legal costs, reputational damage, and lost customer trust.

According to study co-author Dylan Minor, toxic workers are especially dangerous because their behavior tends to spill over. Employees exposed to toxic colleagues are significantly more likely to leave the organization — or to engage in misconduct themselves — driving cascading turnover and replacement costs.

The research also identifies three key predictors of toxic behavior: excessive self-regard or selfishness, extreme overconfidence, and rigid proclamations about rule-following. Counterintuitively, individuals who insist they “never break the rules” were more likely to be terminated for doing exactly that.

Despite their impact, toxic workers often remain employed longer than they should because they are frequently perceived as high performers. Managers may tolerate bad behavior when productivity metrics look strong, underestimating the broader damage inflicted on teams and culture.

The study’s conclusion is clear: hiring decisions that focus solely on upside potential invite risk. Organizations that evaluate both productivity and behavioral risk — valuing cooperation, integrity, and corporate citizenship — are more likely to build resilient, high-performing workplaces.

In short, keeping toxic employees out isn’t just good ethics — it’s sound business strategy.