The All Share Price Index
The ASPI is a market-capitalisation weighted index covering all ordinary shares listed on the CSE. Because it includes every listed stock, it reflects the performance of the entire market including small and mid-cap companies. A strong ASPI day means the market is broadly positive. A weak ASPI day reflects broad-based selling.
The S&P Sri Lanka 20
The SL20 is a float-adjusted market-cap weighted index tracking the 20 most liquid and representative listed companies. It is more stable than the ASPI because it excludes thinly traded stocks whose price moves can distort broader readings. Fund managers often benchmark against the SL20 for performance comparison.
When ASPI and SL20 Diverge
If the SL20 is up but the ASPI is flat or slightly down, the rally is concentrated in large-cap liquid stocks while the broader market is not participating. This is a more cautious environment for small and mid-cap holdings. If the ASPI is up more than the SL20, smaller stocks are leading — often a sign of speculative appetite in the market.
Watch the gap between ASPI and SL20 performance over several consecutive sessions. A sustained divergence where small-caps significantly outperform large-caps often precedes a correction, as the move lacks the institutional volume support that typically sustains a rally.
Index Data on Investography
Both indices are displayed on the Market Overview page with the current value, daily change in points and percentage, and a sparkline showing the intraday trend. The index history is also available through the stock chart interface for longer-term trend analysis.