Mumbai, March 20 -- Dalal Street saw its worst day in more than 20 months on Thursday, as equity benchmarks plunged over 3% in a broad sell-off led by financial sector stocks. Sentiment darkened particularly in private banks, both on stock-specific concerns and a wider risk-off mood. Among the Nifty's top five losers, three were financials-Shriram Finance (-7.0%), HDFC Bank (-5.1%) and Bajaj Finance (-4.9%). At the centre of the selloff was HDFC Bank, whose shares closed 5% lower after falling 9% to hit a 52-week intra-day low. In a shock leadership change, Atanu Chakraborty stepped down as HDFC Bank chairman on Wednesday, with group veteran Keki Mistry taking over as interim chairman for three months. The Nifty ended 3.3% down at 23,002.15...