After Friday's shake-out the downward trend looks set to continue at the start of this week with City traders forecasting the Footsie will open around 30 points lower.More than 100,000 customers of TUI Travel due to return home yesterday were left stranded by the ongoing flight ban imposed after the eruption of the volcano in Iceland last week. Currently, TUI estimates the cumulative cost to the group, up to and including yesterday is circa £20m. Estimated daily costs thereafter will run at approximately £5m - £6m, it added.Cairn Energy subsidiary MedOil has plugged and abandoned a well offshore Tunisia in the Louza block after finding only minor evidence of light oil.The Sage Group has confirmed that its chief executive, Paul Walker, is to stand down "in due course" after 16 years at the helm of the accountancy software company.The performance of Alliance Trust last year was in the lowest quartile of its peer group after the investment trust made a slow start to 2009. Net asset value in the year to 31 January 2010 improved by 16.8% to 377.7p, while the total return advanced 22.2%.