Teacher Retirement System of Texas placed one of the largest single bets on private equity ever by a public employee pension fund, committing $6bn to industry heavyweights Apollo Global Management and KKR & Co.

The $3bn investment with Apollo and $3bn commitment to KKR comes as pension funds turn increasingly to so-called alternative investment strategies such as private equity and hedge funds to help them meet with return targets imperiled by low interest rates and stock market volatility.