Concatenate rows with filter

[sarahhp]

I don't come from a coding background but I'm trying to take a list of products associated with different companies and concatenate the products associated with each company into a single field.  My table has ~5000 products associated with ~1200 companies.  Here's my DAX statement for a measure that's not working:

Product List= CONCATENATEX(FILTER(Table,Table[Company Name]= [MS - Company Name]) ,(Table[Product Name],","))

Thanks for any pointers!