Use the first one.

But, techinically, item is an inanimate object and can't have ownership, so it should actually be

"Statistical information about the activity of the item.

>Hi everybody,
>
>This message seems incorrect to me (in a tooltip):
>
>'Statistical information about this item's activity'
>
>I think it should say
>
>'Statistical information about this item activity' (no preposition here).
>
>What do you think?
>
>Thanks in advance.