Riverstone Energy revealed a dip in net asset value per share on Thursday as it made a loss in the first quarter.The FTSE 250 group said that its net asset value per share at the end of March was $16.26 (£10.29), down from $16.31 at the end of December.Meanwhile, total net asset value at the end of March was $1.23bn, compared to $1.24bn at the end of December.Over the three month period, Riverstone made a loss of $3.7m"Despite the continued volatility in the energy market, we are confident that our disciplined investment strategy, strong capital position and close partnerships with world-class management teams will enable us to capitalise on the current market dislocation," said group chairman Robert Wilson.It is important to note that we have over $700m of cash available to be invested in the current environment," he added.Riverstone was trading flat at 1068p as of 11:45.