British private equity firm TDR Capital has reportedly started an accelerated book build to sell half of its 16% stake in life insurer Phoenix Group. 

According to Reuters, TDR said it intends to offer up to 18 million shares to institutional investors in the process. TDR currently owns 35.9 million shares in Phoenix.

Should it sell all of its shares in the offering, TDR will keep its remaining 8% stake in the London-listed insurance provider. The private equity firm will not sell any more shares in Phoenix for 120 days following the offering's completion, the report said. 

Reuters said that Phoenix's shares closed at GBX704 on Wednesday, valuing the company at GNP158.3 billion. This values the stake being offered by TDR at about GBP127 million. 

TDR Capital is one of United Kingdom's leading private equity firms. It has EUR2.6 billion of commitments under management. TDR has also completed transactions with aggregate purchase price in excess of EUR15 billion, its website said.