1. If one observes heavy open interest in Put call ratio(PCR) building on a single day with implied volatility(IV) reducing then it is a selling by option writers. They are selling the specific option at sale so one can expect market to fall or a correction is ensuing. Winding of calls is bullish whereas winding of puts is bearish. Winding means those who sold options are squaring off their positions.

2. Derivatives markets provide a cue to markets and it is correct most of the time and big boys in options writing business generally make money as they are in tune with the market.

3. A word of caution that a retail investor should not try to get into writing open interest business as it has limited profit potential and a great down side risk.