The Futures Open Interest (OI) in the Nifty indicated a buildup of fresh short positions in index futures. Call writers were seen offloading their positions at the 19,800 strike, leading to a strong down in Nifty today. A double-top structure around the 19,850 levels is visible on the daily chart. A breakdown below the previous swing low of 19,635 can intensify the selling pressure, which can take the index to 19,480 levels, said Ashwin Ramani, Derivatives and Technical Analyst, SAMCO Securities.