Thanks for your response Peter.
I think I do have a lot of exact match anchored links. Are you referring to in-linking on my website, or external inbound links?
I have a large network of websites (geographical location + industry domain names) which all pretty much have the same content, and the exact same links pointing back to my main site. We haven't had time to go through all of our sites yet because we've put all focus on our main website - which had been seeing tons of progress until Penguin hit!
It looks like it was the penguin update that hit us. Our traffic dropped significantly over the weekend, it was relatively normal for the rest of the month of May.
What can I do at this point?