MUMBAI : Mumbai: The benchmark BSE Sensex on Monday dropped by 244 points, its biggest single-day fall in past one month, to close below the key 34,000-mark on the first trading day of 2018 after a late sell-off in auto, banking and IT stocks. The 50-share Nifty cracked below the 10,500-mark to hit a low of 10,423.10 before settling 95.15 points, or 0.90% down at 10,435.55. Investors started booking profit at record highs in absence of cues from global markets that remained closed for the New Year holiday. There was accelerated selling, particularly in the last hour of trading dragging the key Sensex from record highs, brokers said. Bouts of buying were, however, seen in power, capital goods, realty, healthcare and consumer durables sector stocks that capped the losses to some extent. (PTI)