Day Trading Software VWAP Calculation Differences - Iterative VWAP Versus Cumulative VWAP

The Volume Weighted Average Price (VWAP) of aby software firms as it is easier to maintain in the
stock, in basic terms, is the "average" price of thedatabase and prevents the overall software from
stock relative to the amount of volume it has tradedrunning slower than optimal speed. It uses the last
during the day. With greater emphasis on monitoringvalue of VWAP as the basis for calculating the
VWAP due to algorithms impacting intraday tradingVWAP on the next trade. Using the same example
activities, you might be surprised to learn that manyas above:
day trading software firms do not use a standardized- 1st Iteration: (20.05 x 1000) / 1000 = 20050 / 1000
calculation of VWAP! While both calculations will= $20.05
produce similar results, you may wish to contact your- 2nd Iteration: $20.05 + {(20.06 - 25.05) x 800)} /
day trading software firm to ask which VWAP(1000 + 800) = 20.0544
calculation they use if your day trading style warrants- 3rd Iteration: 20.0544 + {(20.04 - 20.0544) x 100} /
monitoring VWAP. Chances are that the(1800 + 100) = 20.0536
representative on the other end of the line may not- 4th Iteration: 20.0536 + {(20.03 - 20.0536) x 2000)
know which calculation is used, so be prepared to(1900 + 2000) = 20.0311
wait a few hours (or even days!) before you get an- 5th Iteration: 20.0311 + {(20.03 - 20.0311) x 3000) /
answer.(3900 + 3000) = 20.0306
The "cumulative" VWAP is considered to be theOf course, as more trades (iterations) are made the
"most accurate" calculation as it changes with everycloser the two VWAP calculations will become. With
transaction. The formula is:each symbol having several hundred (or several
The Sum of all transactions' (Volume in shares x Pricethousand) transactions each day, this should not be a
traded) divided by the Cumulative Volume. Forgreat concern for most day traders. If you happen
example, let's say the stock has 5 trades on the dayto monitor the VWAP for VERY thinly-traded
so far:symbols - with trades happening only a few times a
- $20.05 1000 sharesday - consider asking your day trading software firm
- $20.06 800 shareswhich method they use to calculate VWAP. This is
- $20.04 100 sharessimply so that you know how to monitor the trade
- $20.03 2000 sharesactivity and you then can make any necessary
- $20.03 3000 sharesadjustments to your trading execution methods.
The VWAP would be:You also may wish to talk with your day trading
{($20.05 x 1000) + ($20.06 x 800) + ($20.04 x 100)software firm about other VWAP nuances such as if
+ ($20.03 x 2000) + ($20.03 x 3000)} / (1000 + 800they count pre-market trades in the VWAP
+ 100 + 2000 + 3000)calculation. Find out if you have the ability to plot
This translates into:VWAP on intraday charts alongside indicators such as
(20050 + 16048 + 2004 + 40060 + 60090) / (6900)moving averages. These nuances will give you the
= 20.0365. Therefore $20.0365 would be thebest odds of maximizing your day trading software
"Cumulative VWAP"to help you with your VWAP-related trading.
The "iterative" VWAP calculation is sometimes used