[Interpretation of data like Volume]

Thank you very much! I tried searching before posting but couldn't come up with the right search terms.

Much appreciated!

[Interpretation of data like Volume]

Hi!

Many indicators use volume and other statistics. I was wondering what exactly these refer to.

Let's assume I am spread betting on shares.

Shares are traded e.g. at the New York stock exchange. That means there is a central institution that registers all trades, including price and volume.

Spread betting is a derived product so I am not actually trading the stock.

What does the volume (e.g. if I grab data through the REST API) in this case refer to? Volume of spread bets at IG or is it the actual volume of the underlying share traded at New York Stock Exchange? 

Things get even more indirect if I was spread betting on an index like US500, in this case I assume that volume would not have any meaningful interpretation about price movement at all?

 

Thanks a lot on advance!