South Africa’s bourse suspended trading in the shares of telecoms firm MTN Group on Monday, after the stock fell as much as 8 percent, as Africa’s biggest mobile telecoms operator negotiates to pay a huge fine in Nigeria.

The stock has fallen more than 25 percent in the past seven sessions, wiping out more of the 60 billion rand ($4.36 billion) off its market value, after the Nigerian Communications Commission (NCC) imposed a $5.2 billion fine for failure to cut off unregistered users.

“Yes, trading in MTN shares has been suspended and the information was broadcast across the trading platform,” said Peter Redman of the exchange’s surveillance department.

One trader said the stock tumbled due to speculation the company has agreed to pay the fine.

“There has been some speculation that the company has agreed to pay the fine, but we really want to hear it from the company itself,” said Afrifocus securities portfolio manager, Ferdi Heyneke.

The bourse operator, JSE Ltd, said in a statement that trading in MTN’s shares were halted pending an announcement from the Johannesburg-based company.

NCC on Friday gave MTN Group two weeks to pay the fine.

MTN Chief Executive Sifiso Dabengwa flew to Abuja to try to negotiate a reduced penalty, sources close to the matter said.

Investors also hammered MTN debt with yields on company’s eurobonds soaring to all-time high on Monday. The yield on the paper due in 2024 climbed to a record 5.975 percent by 0905 GMT. The yield on $750 million eurobond due in 2024 climbed 129 basis points in eight days. (Reuters)