ASX staggers the opening based on the first letter of the stock code:
The opening time of the first group is randomized between 9:59:45 and 10:00:15.
Each group opens roughly 2 minutes after the last.
A stock is in an auction when its trading state is non-matching and its bid is greater than or equal to the ask.
Spark considers On Market Trades to be trades that adjust the closing price.
These trades usually adjust all quote figures: the first, high, low, last, volume, and vwap.
Trades that don't adjust the closing price usually adjust volume only.
The Volume Weighted Average Price (VWAP) is an important number for intraday traders and is displayed throughout Spark's tools.
The basic VWAP calculation is a sum of the value of every trade executed during the given period (in dollar terms) divided by the number of shares traded over the same time period.
Spark's VWAP figures take into account the rules set by the exchanges (ASX/CXA) to exclude specific trade types.
The trade types excluded are typically off-market trades executed in the pre/post market trading session. Using the trades tool you can identify the excluded trades by toggling the the VWAP Only button.