While US companies account for just over 60% of the market capitalization of the MSCI All Country World Index, their weight is a tad misleading given that a few technology giants—Alphabet, Amazon, Apple, and Microsoft—weigh heavily on the scale. Together, those four are valued at nearly US$8 trillion, more than the next 15 largest US stocks combined.
Much of the debate surrounding indexing centers on the relative merits of taking an active versus passive investment approach. But the question of how indexing might be reshaping market structure is largely unexplored. The standing assumption is that, since passive investment flows mirror the prevailing distribution of capital, index trades are bereft of information and therefore have no effect on the pricing of the underlying securities; hence the overall scale of indexing is irrelevant. But this assumption becomes more tenuous as the share of passively managed assets grows. What if passive increased to, say, 100% of all equity assets? Would those investments still have no effect on prices?
It’s unclear how the widespread use of indexing may be affecting market structure; that is, at what point the sheer quantity of assets mimicking market behavior could start to change the behavior. Maybe it already has.