Penalised only on new pages?

[giateno]

Hello to all,

we run a strong and popular website, focused on a specific them and always up-to-date. It is leader in its sector and generates a lot of traffic.
Since 10 days, we lost 20% of the traffic and noticed that on all the new content pages we added (linked from the home), for the main keyword, we are in 4th to 10th page, or even not present at all. Using the site: operator, the page is properly indexed. Our old pages have not been penalised (we rank almost always first).

Any ideas?

Thanks!

[danijelzi]

Is there any difference between the new and old pages, such as content length, article uniqueness, link profile? Have you noticed if somebody has scraped your newer pages?

[aristotle]

the new content pages we added (linked from the home), for the main keyword,

Do you mean that all the new pages target the same keyword, which is also the main keyword that some of the old pages target?