Carlyle Group plans to sell its remaining stake in China's third-largest insurer in a deal valued at up to $790 million, marking the US private equity fund's largest gross profit ever from an investment.

After several selldowns of its stake in the last two years, Carlyle will net more than $4 billion profit on the deal, or five times the cash it paid. In private equity terms, a profit of two times cash paid for a gain of several hundred million dollars is considered a successful exit.

The Washington DC-based firm is offering 203 million Hong Kong-traded shares of China Pacific Insurance (Group) Co Ltd in a range of HK$30 to HK$30.30 per share, according to a term sheet of the deal seen by Reuters.

Carlyle invested about $800 million in CPIC between 2005 and 2007 for a 17 percent stake. The firm began to sell its stake late in 2010, exiting portions of its investment in various chunks, culminating in the current term sheet.

Strong demand for insurance products in China coupled with a bull market led to the surge in CPIC's shares.

The firm raised a total of $5.1 billion through its CPIC sales, including the most recent offering. That would put Carlyle's profit from the CPIC deal at $4.3 billion, according to Reuters calculations.

Carlyle's exit of US healthcare company HCR Manorcare is listed at $6.1 billion, but that deal was financed by loans and the gross profit was smaller. Carlyle paid all cash for the CPIC deal.

The sale comes after CPIC's shares surged nearly 40 percent over the past year, reaching a 52-week high last Thursday.

Goldman Sachs and UBS were hired as joint bookrunners for the selldown.

Carlyle's CPIC investment was led by X.D. Yang, Hong Kong-based managing director and co-head of Carlyle Asia Partners.