SEO consequences from transfering tld's to sub domains

Question

We have a client that has multiple top level domains for the products they offer. These products are different full fledged softwares. They also have a domain for their actual company that makes these products. We are consolidating their sites so that all of them can be managed by one backend. One of our developers suggested to consolidate even more by moving their product tld's into sub domains of the company site.

So instead of this:
http://company.com
http://product1.com
http://product2.com
http://product3.com
http://product4.com

It would be this:
http://company.com
http://product1.company.com
http://product2.company.com
http://product3.company.com
http://product4.company.com

They like their current spots they have on search engines for each of these tlds. What consequences would happen they were to move them to sub domains. How (if any) can we prevent these consequences from happening? Or is it better to keep them separate tlds?

Answer 1

If those websites rank well in the search engines making a big change like moving them to subdomains is not advisable. Essentially you are creating new URLs and starting from scratch by doing so. Making a move like that will always result in at least a temporary loss of rankings as Google and the other search engines sort out the new locations for all of that content (see below).

If you do make that move you will need to do 301 redirects for every page on those websites. By doing that you will tell both users and search engines where the content has moved to permanently. It also will tell Google Google to "transfer" incoming links and PageRank to the new URLs. However, the full value of those links are not "transferred" as their is a dampening factor applied whenever a 301 redirect is used so it is possible your rankings will not return to their previous spots.

Your decision comes down to ease of maintenance vs potential search engine rankings drop.

Answer 2

It takes 3-6 months to recover your rankings when doing a 301 redirect from one domain to another. Moving too many domains to one domain can also raise a flag. It's an old SEO tactics to buy lots of domains and point them to a single site increasing its link popularity. Though in your case, you will have the benefit as you are moving all these older domains to subdomains.

Subdomain is considered to be a new site, so the benefit of getting link popularity from main domain is very low. Do it if it makes a lot of branding sense.