The categorisation of countries into relevant international benchmark indices affects the allocation of capital across borders. The reallocation of countries from one index to another affects not only capital flows into and out of that country, but also the countries it shares indices with. This column explains the channels through which international equity and bond market indices affect asset allocations, capital flows, and asset prices across countries. An understanding of these channels is important in preventing a widening share of capital flows being impacted by benchmark effects.