The All Share Price Index (ASPI) is the primary market index of the Colombo Stock Exchange (CSE). It measures the aggregate price movement of every ordinary share listed on the exchange, making it the widest and most inclusive benchmark available to Sri Lankan investors.
The index uses a market-capitalisation-weighted methodology. This means that larger companies — those with higher total market values — have a proportionally greater influence on the index level than smaller ones. A single large-cap stock moving sharply can therefore shift the ASPI significantly even if the majority of listed companies are flat on the day.
Introduced in 1985, the ASPI has served as the official performance benchmark for the Sri Lankan equity market for decades. Financial media, fund managers, and regulators routinely cite ASPI movements as the headline read on the health of the local stock market.
Investors use the ASPI to gauge general market direction, compare their portfolio returns against the broad market, and assess the overall sentiment of domestic and foreign participants in the CSE.