Index providers like MSCI and FTSE classify markets using three quantitative gates plus a qualitative review. The gates are economic development, market size and liquidity, and market accessibility. A country can be reclassified only after surviving public consultation and a staged transition.

Key criteria MSCI applies:

GDP per capita threshold (currently ~$3,500–$5,000 range for EM eligibility)
Equity market capitalization and trading volume minimums
Foreign ownership limits, capital flow restrictions, and repatriation ease
Operational efficiency: settlement cycles, short-selling rules, stock lending

Status	Example	Typical Foreign Access
Developed	South Korea (since 2009 FTSE)	Full, no quotas
Emerging	China A-shares (partial inclusion 2018)	Quota-based (Stock Connect)
Frontier	Vietnam, Nigeria	Restricted, low liquidity
Standalone	Argentina (2019–2021)	Capital controls triggered exit

Reclassification matters because passive flows follow the index. When Saudi Arabia moved to EM in 2019, roughly $20–$30 billion of passive inflows were estimated.