As we have discussed, Nifty has been moving upwards in the channel. It was trading up on the channel. But yesterday, in the last 30 minutes, the fall was very strong. It might be the clear-cut signal of the Bearish market ahead in the week.
Reasons:

1. It has been traveling in the bullish channel side. The fall was sharp, indicating the power for bears is strong at 21800.
2. 21680 has been providing support. If it breaks to the downside, the next direct target will be 200 EMA.
3. According to the OI data, PCR is 0.9. which is mildly bullish. 21700 still has very nice support. If it breaks, bears will be gaining control.
4. in 15 min TF price < EMA(13,50). if there is a crossover, EMA(13,50), the market will turn bearish. and the direct target will be 21500.
5. RSI is near 40 going downwards, which means the market is going to be bearish today.
6. RSI is showing bearish divergence, which means a fall is expected.

most of the points discussed above show that the market is going to be bearish for this week.