Sri Lanka’s stock market slumped further on Monday as fears of slowing economic growth and higher interest rates prevailed ahead of this week’s monetary policy announcement.   The island nation’s main share index fell 0.58 per cent or 32.81 points to 5,456.27, lowest since Feb.19. “The longer it goes like this with low volume and little activities, the investors who stuck will start to sell off. That’s the worry we have in the retail side and we could see the market drift down below 5000,” Stefan Juriansz, technical analyst at Bartleet Religare Securities in Colombo, said.