In the field of private equity investment, secondary funds, also known as PE secondary market, refer to a kind of fund products that specially purchase fund shares, investment portfolios or investment commitments from investors. The biggest difference between S fund and traditional private equity fund is that traditional fund directly buys the equity of the enterprise, and the transaction object is the enterprise; S fund is to buy corporate equity or fund shares from institutional investors, and the transaction object is institutional investors.

The concept of S fund originated in the United States, and its purpose is to meet the needs of private equity investors to improve the liquidity of their fund shares. 1982 the American venture capital group (VCFG Group) established the world's first s fund, focusing on trading opportunities in the private equity secondary market. In the next 20 years, S Fund developed steadily in Europe and America as a niche fund. Until 2004, with the American economy out of the shadow of the Internet bubble, S funds ushered in explosive rapid development. In 2004, the transaction volume reached US$ 7 billion, US$ 27.5 billion in 20 13 and over US$ 40 billion in 20 15. At present, the scale of the largest S fund in the world has exceeded $654.38+000 billion.