So we all know how important anchor text is to SEO. Well, using a comma in your anchor text actually devalues that link. If you are thinking that you want to optimize for many keywords with a link to one webpage, the more keywords separated by commas you stuff into your anchor text, the less “link juice” you will get from that back link.
It’s tough to test things like this out but if you think of it logically, the shorter your keywords are, the more of a chance they get to be ranked high in SERP. When you start adding multiple words and phrases separated by commas, it waters down the entire backlink which just means that you have to get many more back links. Think LEAN.