rollover

Hi all, I am trading in options with reasonable success writing only PUT options of NIFTY and other large cap NIFTY stocks.Trades are usually squared off if 50% profit made in less than a week.Most importantly i am willing to roll over the options to next month if my trade didn't work out.

I have seen very large moves during last half hour of contract expiry. I have heard people say that such moves are due to arbitrage unwinding. Can someone please explain it in detail? Why do these moves take place? Also in some stocks there is an upmove while in others there is a downmove...

Hey, Could someone please tell me the formula or such to calculate rollover in futures and options. I'm talking about both, market wide and stock specific F&O rollovers. I've seen the figures on CNBC, stating 'Nifty rollover stand at 44% with a positive bias', and have tried looking...