Sasol, SA’s biggest company by revenue, said it has held meetings with shareholders as dissatisfaction grows with cost overruns at the $13bn Lake Charles chemical project in the US.

The meetings began after Sasol raised the estimated cost of the project by $1bn in May, having increased it only three months earlier, the company said in a response to questions.

On August 16 Sasol delayed its annual results, saying it has not completed a review of the problems at the project. That prompted its shares to fall the most in 20 years on an intraday basis in Johannesburg.

“The chairman of the Sasol board of directors together with management has held meetings with a number of shareholders to hear their views, concerns and expectations,” the company said on Monday.

“With regard to the specifics of the shareholder meetings, it would not be appropriate for Sasol to comment on behalf of our shareholders on their expectations.”

Problems at Lake Charles, in Louisiana, have hampered Sasol’s plans to expand internationally and to increase chemicals manufacturing alongside its core fuel-production business.

The company’s market value has halved to R169bn over the past 12 months, making it the third-worst performer on an index of Johannesburg’s 40 biggest stocks.

Representatives of Allan Gray, which owns 3.4% of Sasol’s stock, according to data compiled by Bloomberg, have met Sasol’s board about the Lake Charles project, said Andrew Lapping, the chief investment officer of the Cape Town-based fund manager.

He declined to comment on the talks. Coronation Asset Management, SA’s second-biggest money manager by assets under management, which owns Sasol stock, declined to comment.