Concatenate multiple rows using a DAX measure

Hi all,

Here is an example table that i'm trying to write a measure for. My goal is to output a concatenated string of participants for each unique ID.

Participants Conc = CALCULATE(CONCATENATEX(table, <expression>, "; ")

I'm struggling with the expression piece.

My visual will have columns: ID & [Participants Conc]:

Thanks for any suggestions or advice