Q: Why is the volume number for $NYA (the NYSE Composite Index) significantly higher than the value of $NYTV, the "NYSE Primary Market Volume" Index. By the way, the $NYTV appears to match the value for NYSE volume provided by the Wall Street Journal but I can't find the $NYA value anywhere. - Ira H.
A: It turns out the term "NYSE" has two different meanings - something that many people are unaware of. Unfortunately, different publications and sources mix up the two meanings frequently which causes confusion. Here's the distinction:
The term "New York Stock Exchange" (or "NYSE") by itself generally refers to the "NYSE Primary Market" - i.e., the trading floor of the NYSE building down on Wall Street (and its associated computers). On the other hand, the term "NYSE Composite" refers to all of the exchanges throughout the US on which NYSE listed stocks are traded.
What's that? You didn't know that NYSE-listed stocks could be traded on other exchanges? Well, it's true and these days that is where the majority of NYSE-listed stocks actually trade. A good example of that is the BATS exchange which provides us with free real-time data based on those kind of trades.
Anyway, the smaller "NYSE Volume" number (~900 million recently) is the NYSE Primary Market Volume number which is reported by the Wall Street Journal (and by us as $NYTV). The larger number (~4.0 billion presently) is the "NYSE Composite Volume" and is reported on the NYSE.com site, Yahoo Finance, Bloomberg, and elsewhere.
That is the number that we use at the bottom of our "NYSE Composite Index" chart ($NYA).
The good news is that the charts of both numbers look almost identical - both volume numbers rise and fall at almost the exact same rate with similar spikes and drops, etc.