May -15 exp largest close  OI 2700 and it grows the lower it goeshttps://www.cmegroup.com/daily_bulletin/current/Section48_E_Mini_S_And_P_500_Put_Options.pdf
***keep in mind the $SPX contract is twice as big as the $ES and does twice the volume and has 3 to 4 times the OI https://t.co/fJGmg1WCoP