$APO Apollo Global Management (APO -1.8%) is seeking to raise more than $4B for its third natural resources-focused private equity fund, Reuters reports.

P-E firms have been big energy investors in recent years, drawn by the prospect of enjoying significant returns by buying cheap assets whose values were hurt by commodity prices falling from their mid-2014 peak.

Predecessor fund Apollo Natural Resources Partners II raised $3.5B in 2016 and recorded an internal rate of return, net of fees, of 31% as of year-end 2017; Apollo Natural Resources Partners I, which raised $1.2B in 2012, posted a net internal rate of return of 9%.