Check history, almost every year around 17-21 dec #Nifty makes a sudden dramatic fall, though it generally recovers after that. Why does this happen. Speculation is 5th house ruled by #Sun & around 17th Dec Sun enters Mool nakshatra ruled by #Ketu in Sagittarius sign ruled by #Jupiter with Sun as Karaka. Sagittarius is also Finance. See the connections!! And how much Nifty falls (or there is an exception) depends on Jupiter's position at that year in this time!