Riyadh: National Industrialisation Co (Tasnee) made its largest gain for five months, helping the Saudi index bounce back to 17-month highs as investors target the stock, which has underperformed rival petrochemical producers.

Tasnee climbed 4.2 per cent. To Monday's close, the stock was up 2.8 per cent year-to-date, while rival Saudi Basic Industries Corp (Sabic) had gained 16 per cent over the same period.

"Tasnee has underperformed the petrochemicals sector, which is showing continued strength, so investors targeted the stock today," says Saleh Al Onazi, vice-president of principal investment at Swicorp in Riyadh.

Sabic climbed 1.6 per cent to be just below this week's 17-month high.

"As long as oil holds above $80 we will be okay," added Al Onazi.