A sharp plunge in the rupee to record low below the Rs 56-level on Wednesday cost the top stock exchange NSE its trillion-dollar market capitalisation tag, while another bourse BSE managed to hold onto this status just by a whisker. Hit by the double-whammy of declining rupee and stock valuations, the cumulative market value of all the companies listed on the NSE on Wednesday dipped to $999 billion (Rs 55,95,326.34 crore).