Fund manager Vanguard (AUM $6 trillion) has reshaped more than the rural Pennsylvania it calls home, according to an article in the Financial Times that discusses how the firm has reshaped the investment management world and raised questions about whether its girth warrants monitoring.

Specifically, the sheer size of the firm and its “deepening control over the stock market could at some point become unhealthy.”

According to the firm’s CEO, Tim Buckley, the company’s size and income generating prowess allows it to “roll out things like advice, enter new markets…while still lowering your costs to improve your returns.” But this evolution will lead Vanguard to a position of competition with its own client base, the article notes, and plans to expand internationally will “take it into less hospitable terrain.” Further, it argues, “the inexorable tide of passive funds is distorting markets and weakening corporate governance.”

Oxford finance professor Martin Schmalz puts it this way: “If just a few asset managers in practice control most companies, that’s not how capitalism should work.” Morningstar analyst Alec Lucas weighs in: “Vanguard is getting into unprecedented territory. Their growth is something that bears monitoring.”

Vanguard’s increasing size has allowed it to continually slash fees, a “blessing” to clients, but also allows for the distortion of markets and increased “boardroom power” thanks to growing stakes in nearly every major US company. This concern was acknowledged by late founder Jack Bogle who once said “It’s a serious issue, and everyone that says it isn’t, isn’t telling the truth.”

CEO Buckley “cautiously acknowledges” the challenge, the article reports: “We have to make sure we’re talking to companies on how they are dealing with and addressing these issues, but not crossing the line and telling them what to do.”