South Africa’s Sibanye Gold Ltd said it is considering tapping shareholders for up to $1.3 billion to partly fund a $2.2 billion takeover of Stillwater Mining Co, the only U.S. miner of platinum and palladium.

Sibanye had initially penciled in a minimum of $750 million in rights issue but said on Friday it reconsidered after some shareholders expressed concerns about the company’s debt levels.

“Sibanye believes that increasing the equity component would be prudent in the current strong rand environment, allowing the company to maintain a strong balance sheet,” it said in statement accompanying a half-year trading update.