Telstra Corporation Ltd (ASX: TLS) announced today that private equity firms General Atlantic and Apax Partners have agreed to effectively underwrite a planned stockmarket float of SouFun Holdings Ltd, China's second-largest online real estate website where the Australian telecom giant is major shareholder.

According to Telstra, the two firms and two other existing owners of SouFun intend to buy up any shortfall of shares in the business's initial public offer, or purchase the telco's entire 51 per cent stake based on a valuation for the entire company of $US810 million ($A902 million).

While less than the $US1 billion valuation analysts and sources involved in the float have previously flagged, the amount exceeds the valuation of around $US500 million when Telstra obtained its 51 per cent stake in 2006.

This would return Australia's largest telecom provider about $US413 million on the stake, or 39 per cent more than the acquisition price in 2006.

Telstra shares lost 9 per cent on Thursday after it warned a sharp decline in 2011 earnings.

At 1018 AEST Friday, shares are shedding further, down 3.06 per cent at $2.85, against a flat benchmark index.