A significant decline has occurred in the STI, with a drop of 3.5%. This downturn is attributed to surging oil prices. The rise in oil prices has had a profound impact on investor sentiment, leading to the decline in the STI.

Further information on this development is available from the source. The source reports on the STI's performance and the factors influencing it.

Details of the situation can be found through Yahoo Finance, which provides updates on market trends and other relevant information.