Gold Reef Casino Resorts Ltd., whose planned acquisition by Ethos Private Equity Ltd. was thwarted by regulators, rose the most in more than eight years in Johannesburg trading after Tsogo Sun Holdings Ltd. said it may bid.

Gold Reef advanced as much as 4.31 rand, or 19 percent, to 27.01 rand, the biggest gain since December 15, 1999. The stock traded at 26.60 rand as of 9:44 a.m. local time, giving the Johannesburg- based company a market value of 7.8 billion rand (USD 994 million).

“Discussions are at a very preliminary stage and there can be no certainty at all that an offer will ultimately be forthcoming,” Gold Reef said in a statement.

The owner of Johannesburg’s Gold Reef City Casino was told by South Africa’s Securities Regulation Panel on February 1 that it breached rules in accepting a 9.83 billion-rand bid from Ethos after a complaint from Tsogo that said it made a higher offer that wasn’t adequately considered.

Had it been completed, the bid would have been the second- biggest private-equity takeover of a publicly traded South African company after Bain Capital LLC’s 25 billion rand.