Indian equity benchmarks BSE Sensex and NSE Nifty50 are likely to make a gap-down start on Monday, in a U-turn following a jump of almost two percent in the previous session as the RBI's rate hike of 50 bps met Street expectations. SGX Nifty futures — an early indicator of the Nifty index — fell as much as 268.5 points or 1.6 percent to 16,819.5 ahead of the opening bell on Dalal Street.