Why did the Nifty surge in the final minutes of trading today while the Sensex didn't?

Look at the above chart of Nifty 50 which can be seen that the market suddenly closed around 24774.30 why this sudden spike happened in this Nifty 50 index. 

Let me tell you why it happened.

• It surged due in the final minutes due to SEBI's new Closing Auction Session (CAS), institutional buying in specific F&O heavy weight stocks, and structural differences in how index closing values are calculated.

New Closing Auction Mechanism

• CAS Rollout : Monday marked the debut of the Closing Auction Session for stocks in the futures & Options Segment.
• Auction Window : Continuous trading ends at 3:15 PM, Followed by a single price equilibrium auction running until 3:35 PM to determine official closing prices.