The S&P/ASX 200 is a stock market index that represents the 200 largest companies listed on the Australian Securities Exchange (ASX). It serves as a benchmark for the performance of the Australian equity market and includes companies from various sectors, such as finance, healthcare, and materials. Investors and analysts use the S&P/ASX 200 to gauge market trends and make informed investment decisions. The index is weighted by market capitalization, meaning larger companies have a greater impact on its performance. It is widely followed by both local and international investors interested in the Australian market.