Private equity firms are increasingly offering sweeteners such as fee discounts to secure backing from deep-pocketed investors, in a sign that the industry is facing its toughest-ever fundraising environment.

Blue-chip firms including CVC Capital Partners, Ardian, TPG and Cinven have all in recent months offered investors either a discount on management fees or other incentives such as larger amounts of so-called co-investment, which enables investors to get a bigger slice of individual deals without paying a fee, according to people familiar with the matter and fund marketing documents. 

Some firms are even offering big backers such as pension plans and sovereign wealth funds a slice of the management fee that usually goes to the fund manager.