I assume that you defined the variable €œlastFilledRow€� as long, then you
include a line of code to give it value (lastFilledRow = €œcode to determine
last filled row€�).

Then you have all you need to make the fill down work as you have described.
The line of code should read:

Range("StocksFormulas").End(xlDown).Select
€˜Dont know why you are selecting this, not needed for fill down, but maybe
you have another use.

Range("F€� & lastFilledRow & €œ:O30").FillDown

That should work although I am not sure of what area you are trying to fill.
Note the way variables can be used in defining a range.

Tom