As the trend changed in Nifty, sell on rise, medium point of view, 19500 is critical level foe nifty to cross, 20 days and 50 day moving averages crossed on one year chart shows trend negative for at least 3 months, Nifty 19500 put option of Dec expiry can be traded @ Rs 500 to 600.....Nifty is likely to retest the level on 18800 again in Nov expiry.