Last week, Google announced that it has established its own Root Certificate Authority. Google Trust Services will operate Certificate Authorities in behalf of Google and Alphabet. Google has bought existing root certificate authorities Global Sign R2 and R4. Google will continue to operate its GIAG2 subordinate Certificate Authority.
Read more in:
http://www.eweek.com: Google Establishes Independent Root Certificate Authority
http://www.theregister.co.uk: Google launches root certificate authority
https://security.googleblog.com: The foundation of a more secure web
https://pki.goog/: Google Trust Services