AngloGold Ashanti said on Wednesday it would sell its remaining South African assets for about $300 million to Harmony Gold, after announcing it would shrink its portfolio and focus on assets with higher returns.

The gold miner, whose shares fell 3.7% to 275.55 rand by 0800 GMT after earnings rose but not by as much as expected, said in May it would review divestment options for its South African assets, including the world's deepest mine.

AngloGold flagged headline earnings per share (HEPS), the main profit measure in South Africa, for the year to December of 86 cents to 96 cents, up from 53 cents in 2018.

"The minute you see a share come in a little lighter than what the market is pricing in it gets hammered," Independent Securities trader Ryan Woods said.

AngloGold said the deal with Harmony included a cash and deferred payment totalling about $300 million, subject to subsequent performance, with additional proceeds due if the West Wits mines were developed below existing mining infrastructure.

The transaction, subject to approvals by the mining ministry and competition watchdog, could be completed by June 30.

AngloGold said Harmony was identified as the most suitable party to buy these assets during the nine-month sales process, citing its financial capacity and ability to operate ultra-deep, hard-rock mining assets in South Africa.

Rival Sibanye-Stillwater had also made an offer but said last week it doubted its bid would succeed.

AngloGold's South African assets include the Mponeng mine, which is the world's deepest gold mine, as well as a surface rock dump processing business and a mine waste retreatment operation.

AngloGold, which has operations in Australia, the United States, Ghana and Tanzania, previously sold its stake in the Sadiola project in Mali for $105 million.

Harmony, which bought South Africa's Moab Khotsong mine in 2018, said its acquisition of AngloGold's assets provided a strategic, financial, operational and geographical fit.

"The acquisition has the potential to improve our overall recovered grade and increasing our cash flow margins," Harmony Chief Executive Peter Steenkamp said.

The acquisition increases Harmony's South African reserves by 8.27 million ounces, excluding any reserves at Mponeng below the existing mining infrastructure.

AngloGold's South African assets produced revenue of 8.047 billion rand and profit after tax of 331 million rand in 2019, Harmony said.

AngloGold retains its interest in Rand Refinery Limited and its obligations under the Silicosis Class Action Settlement, a legal battle by miners seeking compensation for illnesses they blame on negligence in health and safety.