To make our modeling more realistic, our bars have two times—the start and end times. Other platforms tend to ignore this and have data without time, making modeling a multi-asset portfolio impossible. Markets close at different times, and ignoring this introduces look-ahead bias. 

Previously, we represented daily data from midnight-to-midnight. This covered most cases but confused many people who expected to see the price data a day earlier. We've updated the start and end times of the bar to accurately reflect the market open and close times on a specific day—a new level of precision no other platform provides.

For example, in US Equity markets, Christmas Eve typically closes early. This is represented by a Time value of 9.30 am and an EndTime value of 1.00 pm, accurately reflecting the moment the bar was available. If you were trading another asset, such as FX, which might close at 5.00 pm on Christmas Eve, the FX daily bar would arrive at 5.00 pm later that day. 

These timezone and market-hour-aware daily bars will soon be the default behavior for the platform. Because it is a significant change, we're rolling this out as an optional feature for the next few weeks before making it the default behavior. To opt-in and test the new timed bars early, please use the following algorithm setting:

# Python
self.settings.daily_precise_end_time = True

# CSharp: 
Settings.DailyPreciseEndTime = true;

After July 8th, this behavior will be the default, and to preserve the old timestamps, you will need to set this property to false. We hope this will help make it easier to compare QuantConnect daily data with third-party platforms, as the dates will line up rather than offset one day. 

In live trading, the daily bars will arrive at market close (4.00 pm for US Equities) rather than midnight. If your logic relies on the previous midnight behavior, you may want to review it to be safe.

Happy Coding!

Team @ QuantConnect