Singapore shares edged lower by mid-day after rising for four straight sessions, with commodities firm Olam International and rig builder Sembcorp Marine shedding more than 1% each.

By 1:30 p.m., the Straits Times Index was down 0.1%, or 3.21 points, at 2,891.22. The index has advanced around 9% so far this year, making it the best performer among major Southeast Asian markets.