An article in the NYT describes Vanguard's exceptional growth.
"In the last three calendar years, investors sank $823B into Vanguard funds, the company says. The scale of that inflow becomes clear when it is compared with the rest of the mutual fund industry - more than 4,000 firms in total. All of them combined took in just a net $97B during that period, Morningstar data shows. Vanguard, in other words, scooped up about 8.5x as much money as all of its competitors."
" Vanguard’s assets under management have skyrocketed to $4.2T from $1T seven years ago, according to the company. About $3T of this is invested in passive index-based strategies, with the rest in funds that rely on an active approach to picking stocks and bonds."