Sri Lankan shares closed lower for third straight session on Monday, due to sharp losses in industrial and energy companies.

The CSE All-Share index, coming of its biggest quarterly gain in 12 years, settled 2.83% lower at 9,649.86, its lowest since Sept. 8.

The Colombo Stock Exchange said in the final hour of the session that trading had been halted for rest of the day due to a drop of more than 5% in the S&P SL20 index.

“Sri Lanka reduced its petrol prices unexpectedly by 40 rupees over the weekend, which sparked a sell-off on Lanka IOC shares. Shareholders were clearly hoping for continued high prices and that is being reflected in the market,” said Sanjeewa Fernando, head of research at CT CLSA.

Lanka IOC, the local unit of Indian Oil Corp , was among the top drags on the market, dropping as much as 7.2% in its biggest intraday loss since Aug. 15. The stock closed 6.9% lower.

Sri Lankan shares record best quarter in 12 years

Conglomerates Expolanka Holdings Plc and LOLC Holdings Plc also weighed on the index, falling 12.5% and 4.8%, respectively.

Trading volume on the CSE All-Share index rose to 125.4 million shares on Monday, from 99.4 million in the previous session.

The equity market turnover was 2.54 billion Sri Lankan rupees ($7 billion), compared with 2.58 billion rupees in the previous session, according to exchange data.

Foreign investors were net buyers in the equity market, purchasing 52.6 million rupees worth of shares, while domestic investors were net sellers, offloading 2.53 billion rupees worth of stocks, data showed.

Despite the losses in the last two sessions of last month, the CSE All-Share index had clocked a gain of 35.26% from July to September, its biggest quarterly jump since September, 2010.