The billionaire investor Ronald S. Baron flashed the grin of a proud father at his annual investor jamboree in November, as the chief executives of his favorite companies explained how slashing prices stoked their bottom lines.

That is, until a shareholder in one of his mutual funds drew an awkward parallel.

“Excuse me — Schwab is charging a very low fee,” a woman pointed out, after a presentation by Walter W. Bettinger II, the chief executive of the discount broker Charles Schwab. “God bless him, but no one ever said Baron’s fees are little.”

You can say that again.

Mr. Baron’s mutual funds charge some of the higher investment fees around, and the fees have held steady despite a $1 trillion exodus out of old-school mutual funds into cheaper, better performing rivals that track a variety of indexes and investment styles.

In a global economy where competition and Amazonian price destruction have forced companies to cater to cost-wary customers, the mutual fund industry is a rare outlier. Fees on most actively managed mutual funds, which house the retirement savings and other assets of millions of Americans, have barely budged.