Set stock BY or ON?

First post here.
English (British) mother tongue.

Hello all! Let me say it is very nice to have found these boards.

I've Googled quite thoroughly but cannot seem to find a solution to my problem. Is the correct phrase "to set stock by" or "to set stock on" something?

The context is :
"Critics have been overruled by believers in freedom of expression who set stock by the judgement of consumers ..."

I'd be really pleased to hear some views and in particular to find some copper bottom references.

Cheers everyone, and thank you very much for any input.