Reliance Industries Ltd on Thursday managed to restart the vacuum gas oil hydrotreater unit that had to be shut down on Wednesday after it caught fire.
A company statement late on Thursday said that the production of the VGO hydrotreater unit was back to normal and operating at full capacity.
It also said that the refinery was producing LPG at the normal rate of 7,000 tonnes per day.
Earlier, the Reliance scrip fell by Rs 18.95, or nearly 1.59 per cent, including a sharp fall after 3 pm, pushing down its market capitalisation to Rs 1.63 crore.
The fall dislodged RIL from the top position in terms of market capitalisation on the BSE Sensex, paving the way for ONGC to regain the top position on the index.
ONGC shares rose 0.43 per cent, helping push its market cap to Rs 1.64 lakh crore.
The share prices of petrochemical companies as well as oil refining and marketing companies took a beating on Thursday despite extremely low volumes.
Reliance Industries Ltd, Indian Petrochemicals Ltd, Bharat Petroleum Corporation Ltd and Hindustan Petroleum Corporation Ltd, fell sharply from their post-Diwali prices.
The stocks slipped due to overbought positions on the futures and options side, dealers said.
Rollover might not have been smooth on the derivatives side on these counters, said a dealer with Parag Parekh Securities.
The situation was further compounded by speculation in the market regarding the extent of damage at the Jamnagar refinery.
The drop in HPCL and BPCL scrips were linked to the hike in crude oil prices globally.