Needed here as well!
need this bad.
I fully agree, we’re facing the same issue
hey everyone, i resolved this issue. Not perfect, but I found that if I add a new property to the object, and made the property type a hubspot user, then the hubspot user added has view access to the deal. This allowed me to hide all deals unless you own them, but also give visibility to users added to the new custom property view access as well.
Hello chanceabbott
Good news, thanks! With this new property, is the hubspot user added able to modify the deal or is it a view-only access?
Would be much appreciated if this could be added to a workflow.
Needed! Same with deal splits too!
Would love this to be implemented!!!
we need this as well
Any idea of when this might be available?
Any updates here on this? We also would want to be able to add Deal Collaborators via API if possible. 
Upvotting this request. This is a crtical need! Please provide update as to when this will be available.
Yes, please make this change!
It would be great if this was implemented!
Does anyone know if the HS Product team is working on this?
+1, this would be an excellent feature, take out alot of manual work, and save teams time. This could also help improve the reporting in dashboards and goals.
Agreed, needed to do from a workflow, very limited value if only a manual option as of today
twenty-firsting this idea
This functionality is now supported! Learn more here.