stabilize an over subsribed

#1
hi friends..
recenty i was reading about IPO's/FPO'S/book building etc...

one question that came across my mind that-

if a stock is trading above the offer price i.e. it is over subscribed or the investors are showing confidence in the listed stock...then why do we need to stabilize the stock and bring the market price down by exercising the green shoe
option??????:confused::confused:

please address this...it is really baffling me and i cant find answer to this any where on the internet!!!:(:(