The story
In June 2003, Seiko Epson became public following their listing on the 1st section of the Tokyo Stock Exchange. Since then, Seiko and the Hattori family have reduced their holdings in Seiko Epson. Although Seiko Group Corporation (f/k/a K. Hattori, Hattori Seiko, and Seiko Holdings) and the key members of the Hattori family still hold approximately 10% of the outstanding shares of Seiko Epson, the company is managed and operated completely independently from Seiko Group. Epson is several times larger than the Seiko Group in terms of revenue and market cap. It has established its own brand image and rarely uses 'Seiko.'
As of October 1, 2009, Seiko Instruments (SII) was merged into Seiko Holdings and became a wholly owned subsidiary of Seiko Holdings.
In 2020, Seiko Instruments transferred its watch business (including its luxury mechanical watch studio, Morioka Seiko Instruments in Shizukuishi, Iwate) to Seiko Watch Corp. and no longer produces SEIKO watches while it supplies watch parts such as quartz crystal resonators and micro batteries to the watch productions.
On October 1, 2022, Seiko Holdings Corporation renamed Seiko Group Corporation. Currently, the original K.Hattori & Co., Ltd. (服部時計店, Hattori Tokeiten) is a holding company called "Seiko Group Corporation" and holds the Seiko companies including Seiko Watch, Seiko Instruments, Seiko Time Creation, Seiko Solutions, Seiko NPC, Seiko Future Creation, Ginza Wako, etc.
Seiko Watch Corp., a subsidiary of Seiko Group Corp., markets SEIKO watches while its subsidiaries Morioka Seiko Instruments, Tono Seiki, Ninohe Tokei Kogyo and foreign subsidiaries manufacture their mechanical and quartz movements. Seiko Watch delegates the manufacture of some of its high-end quartz and spring drive watches (Seiko Astron, Grand Seiko, Credor, etc) to the Wearable Products Operations Division of Epson.
Time Module (TMI), a member of the Seiko Group, was established in 1987 with funding from Seiko Watch Company, Seiko Instruments Inc., and Seiko Epson Corp. to manufacture watch movements. Currently, TMI is wholly owned by Seiko Group Corp.
From Wikipedia’s article on Seiko Group, shared under CC BY-SA 4.0.4