I am currently watching a stock but I noticed as the volume increased the bid/ask never changed. Why would that happen?
Without further context it is hard to be specific, however I suspect that something along these lines is occurring :
If the number of shares being offered at the current ask price is greater than the number of shares being bought during the period of increased volume, then the ask price will remain until all of those shares being offered are sold.
For example, if there is one or more large sell orders at the current ask price and involving many thousands of shares, then it may take many smaller buy orders to fill the outstanding sell orders. Until the sell orders are completely filled, the ask price will remain in the market.
And similarly for the bid price.