▁ ▁Crit ics ▁ ▁Crit ics ▁of ▁Pi qq em ' s ▁approach ▁assert ▁that ▁the ▁stock ▁market ▁already ▁reflect s ▁the ▁wisdom ▁of ▁crow ds ▁in ▁its ▁pr icing ▁method ology . ▁Pi qq em ▁ended ▁its ▁Twitter ▁operations ▁ 1 9 ▁July ▁ 2 0 1 0 . ▁ ▁References ▁ ▁External ▁links ▁Pi qq em ▁Home page ▁Pi qq em ▁B log ▁ ▁Category : Comp an ies ▁based ▁in ▁Santa ▁Clara ▁County , ▁California ▁Category : Fin an cial ▁services ▁companies ▁established ▁in ▁ 2 0 0 8 ▁Category : In vest ment ▁management ▁companies ▁of ▁the ▁United ▁States ▁Category : Pred iction ▁mark ets <0x0A> </s> ▁P ert urb - seq ▁( also ▁known ▁as ▁CR IS P - seq ▁and ▁C ROP - seq ) ▁refers ▁to ▁a ▁high - through put ▁method ▁of ▁performing ▁single ▁cell ▁R NA ▁sequ encing ▁( sc R NA - seq ) ▁on ▁po o led ▁gen etic ▁perturb ation ▁screens . ▁P ert urb - seq ▁comb ines ▁multiple x ed ▁CR IS PR ▁medi ated ▁gene ▁in activ ations ▁with ▁single ▁cell ▁R NA ▁sequ encing ▁to ▁assess ▁compreh ensive ▁gene ▁expression ▁phen ot ypes ▁for ▁each ▁perturb ation . ▁In fer ring ▁a ▁gene ’ s ▁function ▁by ▁applying ▁gen etic ▁perturb ations ▁to ▁knock ▁down ▁or ▁knock ▁out ▁a ▁gene ▁and ▁studying ▁the ▁resulting ▁phen ot ype ▁is ▁known ▁as ▁reverse ▁gen et ics . ▁P ert urb - seq ▁is ▁a ▁reverse ▁gen et ics ▁approach