Since the financial crisis almost a decade ago, low interest rates and cheap debt have boosted capital piling into private equity funds by investors looking for higher returns. But rising valuations have made it harder to achieve high returns, so much of the money sits idle.

According to industry data provider Preqin, this fund brings total buyout fundraising in the first seven months of 2017 to $184 billion meaning the year will likely surpass the last record for buyout fundraising, in 2007, when funds closed through the year raised $249 billion.

"Fundraising in 2017 so far has been dominated by the re-emergence of record-breaking funds," said Christopher Elvin, Head of Private Equity Products at Preqin.

"However, Apollo may not hold the title for that long: there are two other private equity funds currently in market which have larger targets, and which may be looking to hold a final close in the coming months."

Delaware-incorporated Apollo Investment Fund IX, L.P. surpassed its $23.5 billion hard cap and intends to reach $24.7 billion in total, the filing from the Securities and Exchange Commission showed.

Prior to this Fund VIII closed in December 2013 with more than $18 billion of commitments.

Led by industry veterans, Leon Black, Joshua Harris and Marc Rowan, Apollo has investments in private equity, credit, real estate and publicly managed funds. It has around $45 billion under management in private equity.

In June, CVC Capital Partners raised the biggest ever Europe-based fund with 16 billion euros ($18.69 billion) for private equity investments in Europe and North America.

(Reporting by Dasha Afanasieva, editing by Pritha Sarkar)

By Dasha Afanasieva