Retail Trading Chart Data Accuracy FAQs
For traders doing internet based trading, charting data is crucial in deciding the entry and exit of stock/scrip they are interested in. Thus chart data accuracy is of utmost importance.
Tick By Tick vs Multicast data
The data coming from exchange has different source and the accuracy of the chart data (Open,High,Low,Close,Volume or OHLCV) created depends on that. Those are-
a)Multicast UDP data: It contains aprrox. 1 tick per second per scrip
b)Tick By Tick data(TBT) : It contains all the ticks per second per scrip
Almost all brokers in India use multicast data for broadcast on Market watch and for creating chart data which is accurate enough for retail traders to take their trading decisions. But people who need 100% accurate trading data (may be for their strategy based trading), need to contact authorized data vendors in India or directly exchange to purchase this data. More details for NSE exchange is here.
As we can see, using Multicast data source, chart data won’t be 100% accurate unless data source used is TBT. Hence,to help the brokers, exchange comes up with a Bhavcopy data at the end of the day, which has the day’s correct (OHLCV). The brokers who are providing daily chart(EOD chart) to their clients adjust the chart data(after trading hours) accordingly to the bhavcopy data. Thus, the EOD chart will be 100% accurate as per TBT. Hence, people doing backtesting on EOD data will not be affected at all (even the data source is Multicast data).
Pre Market Open Session
Note:For Nifty Stocks(for NSE CM) and Sensex stocks(for BSE CM) Pre Market session is 9:00 am to 9:15 am (generally till 9.07am ,rest 8minute is buffer period)
Pre Market Open Session is conducted to find out the Open Price or Equilibrium price for the trading day. More details about Pre Market as per NSE official site is here .
Thus,Open price for a minute chart (which is the 1st Last Traded Price) at 9.15 am may not match with the open price of EOD chart(adjusted with bhavcopy which also contains equilibrium price).To have a real example for 8th December for INFY-EQ of NSE CM:
As seen from Screenshot 1, Equilibrium price of INFY-EQ is 970.05, hence in the EOD chart and bhavcopy too the Open price would be 970.05. In Screenshot 2 which is a minute chart we can see the Open price as 971.55.
Thanks for reading!