“You absorb the culture and you join the cause,” said Joseph Brennan, who, as head of global equity indexing, has had a front-row seat as the firm has expanded. His division embodies Vanguard’s credo of do more with less: The 45 people he oversees globally look after $2 trillion in assets.

“Our assets per head are incredible,” he said. At $44 billion per person, that certainly qualifies as an understatement.

Up and down Wall Street, where the sum of a firm’s assets under management has become a badge of power and sway, Vanguard’s ability to attract and run so much money with so few people has been a cause for envy and disbelief. Some have even warned that index funds will distort the broader market, especially if active stock pickers are pushed farther to the sidelines.

Already, six out of the 10 largest mutual funds by asset size belong to Vanguard, with the largest, Vanguard Total Stock Market Index, now weighing in at $465 billion, according to Morningstar. Only two — American Funds’ Growth Fund of America and its EuroPacific Growth Fund, both belonging to the Capital Group — are actively managed, promising higher returns for a steeper fee.

“There is this existential crisis in the soul of every professional asset manager,” said Josh Brown, a financial adviser and blogger at Ritholtz Wealth Management. “Vanguard has become synonymous with the idea that people should pay less — not more — for stock market exposure.”