Blackstone Group LP set a $25 billion cap on its latest flagship buyout fund as investors clamor to get into the offering, according to people familiar with the matter. New York-based Blackstone has attracted more interest from investors for its eighth private equity fund than it’s willing to handle, said the people. At $25 billion, Blackstone would exceed Apollo Global Management LLC’s $24.7 billion fund, an industry record. Blackstone and its peers are benefiting from a robust fundraising market as investors continue to express confidence in the return potential for the asset class.