I wrote a major report and our client put it online. How to present it in a CV?
It sounds eminently sensible to put that into your CV to me: it shows you can write articles for a technical audience, and get the articles past some kind of review process, which in some sense is a researcher's job.

There's no law on how to express it, it depends how the rest of your CV is arranged. I might adjust your "Presentations" header to be "Selected presentations and reports", and then right at the top,


  I was the leading author on 100-page blah blah report for a commercially vital client of $xyz billion dollar turnover company; report available at www.xyz.com/