On Thursday, within a five-minute window after the start of CAS on BSE—between 3.18pm and 3.23pm—sensex crashed over 2,200 points and then within the next seven minutes—between 3.23pm and 3.30pm—it recovered nearly 2,000 points. It finally closed at 76,934 points, down 539 points from its Wednesday close. On NSE, things were relatively quiet. Between 3.18pm…