You may create Stocks report by choosing this option from Add Report dropdown.
Note, that Stocks report is only available, if option Use Drills is enabled in the Settings step.
Stocks report is similar to a pivot table report. It represents statistics that summarize the available stocks data from the database.
To create stocks report drag fields from the data panel in the upper right of the screen down to the Filter/Column/Row/Data Areas in the lower right of the screen.
Overview and detailed description of fields and panels for this types of reports see here (as they are similar to the pivot type report).
