It has been a week of steep drops for some emerging-market stocks, but Sasol has out-plunged its peers, battered by the crash in oil prices and concern among investors of a potential looming rights offer as it grapples with a debt burden of about $8 billion.

After a 47% crash on Monday, Sasol lost more on Tuesday, and then fell another 25% on Wednesday afternoon. It was last trading at R53.85 - less than a year ago it was above R470.

Sasol has now lost more than 65% since the week started, the most among the 1,401 members of the MSCI Emerging Markets Index, which is down 5.6%. The latest slump has dragged the stock to levels last seen in early 2001.

Sasol delayed an investor call scheduled for Tuesday until March 17, noting that its oil-price exposure for the rest of the fiscal year is not hedged. While the company had assumed oil will stay in a range of $50 to $70 a barrel, Brent crude traded just above $36 on Wednesday.Sasol is now valued at R32 billion by the market - while its debt burden exceeds R121 billion.

Investors are worried that the collapsing oil price may be forced to issue more shares to raise cash.

There are concerns that its debt covenants which may be breached. Some of Sasol's loan conditions require that its debt-to-profit levels remain above a certain level. Sasol's profits will take hit a from the lower oil price, which will probably leave it in breach of these debt covenants. This means that its loans could become payable immediately.

The yield on Sasol's $750 million of notes due in 2028 climbed for a sixth day to a record 6.93%.

Sasol’s 0.6% weighting in the benchmark JSE's all share index has limited its impact on the overall market. Among emerging markets, Poland’s WIG 20, Russia’s dollar-denominated RTS Index and Saudi Arabia’s Tadawul All Share Index have been the worst performers this week, falling at least 12%, while South Africa’s gauge has dropped about 5.7%.