Effecting from 17th June 2015
If you need to make the closing price unchanged to avoid the force selling, make sure at least 100 shares to buy at a highest offer within last one hour. But it will not work if the stock was traded heavily at a bottom price during that hour. So don’t even try for that.
http://www.cse.lk/cmt/upload_cse_announcements/7651434003208_.pdf