Hi,
Currently, the only report available in AdWords API for negative placements is the
Campaign Negative Placements Performance Report. The AdWords API has no account level reporting for negative placement. Also, you may take note that negative placements do not hold statistics. However, you can use this structured report to efficiently retrieve attributes of placement-based
NegativeCampaignCriterion objects.
With regards to creating account level negative placement, you may check to this
guide for your reference which also includes sample codes.
For reporting on shared sets, you can see on this
link the available report types supported for shared sets.
Let me know if you have further clarifications.
Thanks and regards,
Luis
AdWords API Team