Sources: Morningstar (ownership); S&P Global Market Intelligence (S&P 500 constituents, share classes, outstanding share counts and stock prices)
Methodology
The Wall Street Journal worked with Morningstar Inc. to compile a list of all U.S.-based mutual funds and exchange-traded funds that can invest in the S&P 500 whose investments Morningstar tracked from 2005 through the present year. Morningstar classifies ETFs and mutual funds as active or passive.
Using the Morningstar data, the Journal tracked each fund's reported stock holdings at the end of each year from 2005 to 2015 and at the end of June 2016.
Using data from S&P Global Market Intelligence's Xpressfeed service, the Journal determined which companies—and which share classes of those companies—were included in the S&P 500 index at the end of those same periods. The Journal used that list to extract the mutual fund and ETF holdings of S&P 500 companies.
The Journal then calculated what percentage of the S&P 500's total value and what percentage of each company was held by passive mutual funds and ETFs and what percentage was held by active mutual funds and ETFs across the years in the analysis.
The analysis reflects S&P 500 ownership for U.S.-based mutual funds and ETFs tracked by Morningstar. The analysis does not include funds based overseas, separately managed accounts, or other types of active and passive strategies pursued by a range of institutional and other investors.