Sharethrough can support IAS viewability tags on The Trade Desk, AppNexus, DBM and Brightroll; however, these tags must be modified with Sharethrough macros before being implemented.
The steps in the process are:
1. Send IAS tags to your Sharethrough rep for modification
2. Paste the returned impression pixel URL into the DSP's UI.
As with any tag, any unexpected edits to the code (extra punctuation or spaces, an incorrectly capitalized letter) will break the tag.
Please reach out to your Sharethrough rep for with questions.