Stock market size can be measured in various ways, and each may produce a different ranking of countries.

The development of an economy's financial markets is closely related to its overall development. Well-functioning financial systems provide good and easily accessible information. That lowers transaction costs, which in turn improves resource allocation and boosts economic growth. Both banking systems and stock markets enhance growth, the main factor in poverty reduction. At low levels of economic development commercial banks tend to dominate the financial system, while at higher levels domestic stock markets tend to become more active and efficient relative to domestic banks.

Open economies with sound macroeconomic policies, good legal systems, and shareholder protection attract capital and therefore have larger financial markets. Recent research on stock market development shows that modern communications technology and increased financial integration have resulted in more cross-border capital flows, a stronger presence of financial firms around the world, and the migration of stock exchange activities to international exchanges. Many firms in emerging markets now cross-list on international exchanges, which provides them with lower cost capital and more liquidity-traded shares. However, this also means that exchanges in emerging markets may not have enough financial activity to sustain them, putting pressure on them to rethink their operations.

The S&P Global Equity Index Series covers approximately 11,000 securities from over 80 countries. It includes the S&P Global Broad Market Index (BMI), S&P Global 1200, S&P/IFCI, and S&P Frontier BMI. All indices are float-adjusted, market capitalization-weighted indices and include security classifications for country, size, style and industry.

The S&P Global Broad Market Index (BMI) is a global index suite with a transparent, modular structure that has been fully float adjusted since 1989. This index series employs a transparent and consistent methodology across all countries and includes approximately 10,000 stocks from 26 developed and 20 emerging markets.

The S&P Global 1200, a real-time, tradable global equity index covers approximately 70 percent of the world's market capitalization, giving a detail view of the world economy. It is a composite of seven headline regional indices: S&P 500®, S&P Europe 350, S&P TOPIX 150, S&P/TSX 60, S&P/ASX All Australian 50, S&P Asia 50 and S&P Latin America 40.
S&P Global Equity Indices (annual % change)
The percentage change in stock market prices in U.S. dollars for developing economies is from Standard & Poor's Global Equity Indices (S&P IFCI) and Standard & Poor's Frontier Broad Market Index (BMI). The percentage change for France, Germany, Japan, the United Kingdom, and the United States is from local stock market prices.

The indicator is an important measure of overall performance. Regulatory and institutional factors that can affect investor confidence, such as entry and exit restrictions, the existence of a securities and exchange commission, and the quality of laws to protect investors, may influence the functioning of stock markets.

Because markets included in Standard & Poor's emerging markets category vary widely in level of development, it is best to look at the entire category to identify the most significant market trends. And it is useful to remember that stock market trends may be distorted by currency conversions, especially when a currency has registered a significant devaluation.
S&P Global Equity Indices measure the U.S. dollar price change in the stock markets covered by the S&P/IFCI and S&P/Frontier BMI country indices.
Ratios of end-of-period levels in U.S. dollars over previous end-of-period values in U.S. dollars times 100. These indexes are widely used benchmarks for international portfolio management.