Reliance Industries Ltd reported a flat profit for the second quarter on Friday, as export taxes on refined fuels and weak refining margins weighed down the dominant oil-to-chemical business at India’s most valuable company.

The Indian government’s decision to levy windfall tax on exports of gasoline, diesel and aviation fuels in the second quarter hit profit by 40.39 billion Indian rupees ($488.42 million), Reliance said.

The oil-to-chemical (O2C) business, which witnessed strong momentum over the past few quarters on the back of cheap Russian crude and higher demand for transportation fuels, also saw refinery margins cooling off from record highs in the quarter.

“Performance of our O2C business reflect subdued demand and weak margin environment across downstream chemical products,” Mukesh Ambani, chairman and managing director of Reliance, said in a statement.

Earnings before interest, taxes, depreciation, and amortization (Ebitda) in the O2C segment dropped 5.9% year-on-year to 119.68 billion rupees, its first drop in six quarters.

Even as Reliance has diversified its businesses over the years to retail, telecom and recently to green energy, O2C continues to be the strong revenue generating machine. The O2C segment’s revenue rose about 33% to 1.6 trillion rupees.

The conglomerate’s consolidated profit was 136.56 billion rupees in the quarter ended Sept. 30, compared with 136.8 billion rupees a year earlier.

Production meant for sale of refined products was down 3.6% as the company shut a crude distillation unit and gasoline-making fluid catalytic cracker at Jamnagar in western India in September for usual maintenance, the company said.

The retail business, which suffered the most in coronavirus-led lockdowns, saw revenue growth of 42.9% as footfalls continued to surge, while the telecom unit Reliance Jio reported a 28% rise in profit for the quarter.