I have a field "price" that updates once a stock is entered. this then calculates Market value for the holding by using the after update function and calculating the market value by multiplying quantity (already present in another field) by the price that has updated. Problem is that I may want to update the price and would like the market value to update again. I use the after update function again but this time it doesn't do anything. First after update was run after updating "stock" the second after updating "price". Is there a bug or a setting I'm missing, as far as I can tell I don't see why I shouldn't be able to update fields a second time.

If you do not make a change in the field there is nothing to 'update'. You have to make a physical change to the data in the field before the After Update event will fire....

On After Update of PriceTextbox
Me.PriceTextbox.Requery