If you looked at today's NIFTY or NIFTY50 stock charts and wondered why the last candle suddenly became much larger after the market closed, you're not alone.

At first glance, it looks like a data error. In reality, it's the result of NSE's new **Closing Auction Session**, which has now gone live.

Here's what actually happens.

- The regular trading session ends as usual.
- No new intraday candle is added after the close.
- NSE conducts its Closing Auction to determine the official closing price.
- Once the auction is complete, TradingView (and most data vendors) update the **existing final candle** with the official closing price.

The interesting part is that the number of candles does **not** change.

https://www.tradingview.com/chart/Dlxqjasj/

For example, on a 1-minute chart you won't suddenly see extra candles after 3:30 PM. Instead, the last candle is revised. Its Close—and sometimes even its High or Low—can change significantly if the auction price differs from the last traded price during continuous trading.

This explains why today's final candle appeared much larger than expected.

## What does this mean for traders?

**Swing traders:**
https://www.tradingview.com/chart/QMEp1WCr/
Nothing really changes. The official closing price has always mattered, and your daily charts will now simply reflect the auction-determined close.

**Intraday traders:**
https://www.tradingview.com/chart/Dlxqjasj/
Don't assume the final candle is "finished" immediately after the market closes. It may still be updated once the auction concludes.

**Indicator users:**

Indicators based on the last candle—such as ATR, candle range, momentum or volatility—may occasionally show a larger-than-normal final candle because it now incorporates the auction adjustment.

## My observation

One implementation detail stood out while examining today's data.

TradingView doesn't create a separate "auction candle." Instead, it updates the existing last candle after the auction price is finalized. This keeps the candle count unchanged while ensuring that the chart reflects the official NSE closing price.

So if you notice an unusually large final candle going forward, it's probably not a charting issue. It's simply the market's official closing price being incorporated into the last bar.

Have you observed the same behaviour on your charts today?