Drop in indexed pages, penalty?

Hi peeps,

In Google Search Console i can see that there are 2988 pages indexed by Google, but when i dig deeper in the indexstatus chart it is showing me that there are only 244 pages indexed and i am seeing an enormous drop in indexed pages on the 5th of may. We did not change anything on our websites. Could we be targeted by an penalty?

Thanks in advance

Did you make some change in your robot.txt / htaccess or other files, or maybe your permalink structure which could affect your indexation ?

any https redirection or removal of sitemap?

Thanks for the response guys.

I've figured out the issue. We have recently launched a blog on our subdomain. All blog articles are redirected to the subdomain. This ofcourse affected the total numer of indeed pages. The old blog article pages are still visible in the xml sitemap of our main domain, thats why i think there is a difference between the 2 screenshots.

What is your guys opinion on placing a blog on a subdomain? I've already noticed a big drop in the SERP positions....

I think that moving a blog to subdomain is a bad decision for SEO.
A subdomain is treated by the search engines as an unique website.

You can read interesting articles at:
goo.gl/QQz7CG
goo.gl/1lhgMx

And you can find more info searching Google.
Just search in Google:
"Subdomains vs Subfolders SEO"
"Subdomains vs Subdirectories SEO"