IIRC, FS bought Regent Hotels in the mid to late 90s and the then current Regent Hotels (Sydney, Hong Kong, Beverly Wilshire, SIN, BKK, TPE, etc) were incorporated into FS, eg, The Regent Bangkok, a Four Seasons Hotel. Within the last couple of years FS sold the rights to the Regent brand to Carlson Hotels but retained management of the aforementioned Regent Hotels. Since then, the Regent HKG was sold and Sydney, Bangkok, Chiang Mai and Jakarta have been re-flagged as FS hotels. FS still has management of Beverly Wilshire, Taipei, and Singapore.

New Regent Hotels, like Ningbo, Zagreb, and Berlin, etc are under Carlson management and are, AFAIK, divorced from FS.

I think I have it right...... if not, I am sure others will correct any errors I have made.