Founder-CEOs can hurt a company's fortunes if they stay too long after IPO, researchers found. : Investors and execs can be divided on the question, but researchers believe they've worked it out: any time in the three years after IPO. Not only should founder-CEOs step down within three years of taking their company public, staying longer could have a detrimental effect on the firm's value, according to preliminary findings from researchers at the University of North Carolina and the University of California.