Now, here's the logical trick: since the sum - total of active and passive investments matches the market, the proportion allocated to any market
segment by active managers must, in aggregate, equal the allocation made by passive investors.
Not exact matches
Since you own a bit of every company, your index investment is wholly aligned with the returns of the stock market
segment tracked
by that index — as opposed to the performance of a fund
manager (with an
active fund) or individual companies (with your own stock picks).