LAGOS — Investors on the Nigerian Exchange gained about N1.5 trillion during the week as the All-Share Index rose 0.92 per cent to 252,113.41 points, bringing the year-to-date return to 62.01 per cent. Market capitalisation reached about N163.66 trillion. A total of 4.69 billion shares worth N240.96 billion changed hands. The oil and gas index rose 3.49 per cent and banking 3.06 per cent.