| 1923-09 |
Scheduled to be announced in September 1923 (Taisho 12), but the Great Kanto Earthquake occurred just before, causing unprecedented chaos and temporarily halting the process. |
| 1923-12 |
Decided at the Mitsui General Meeting in December 1923. |
| 1924-03-25 |
On March 25, 1924, a founding general meeting was held at the Japan Industrial Club in Marunouchi, establishing Mitsui Trust & Banking Co., Ltd. as one of the direct subsidiaries of Mitsui General Partnership, with Takuo Toma as Chairman of the Board and Yoneyama as President. |
| 1924-04-10 |
On April 10, 1924, licensed for trust business and collateral trust bonds business, and began operations on April 15 of the same month. |
| 1924-04-15 |
Started operations on April 15, 1924. |
| 1924-07 |
In July 1924, Sumitomo Joint Stock Company drafted a plan to establish a trust company, and Sumitomo Bank's Board of Directors and Sumitomo Joint Stock Company decided to establish it. |
| 1925-04 |
Proposed the establishment purpose statement in April 1925. |
| 1925-06 |
Completed the subscription of 4 million shares with a capital of 200 million yen in June 1925. |
| 1925-07-28 |
Sumitomo Trust was established on July 28, 1925, with the inaugural general meeting held at Nomura Building in Osaka. |
| 1925-09-02 |
Sumitomo Trust commenced operations on September 2, 1925. |
| 1926-08 |
Opened Tokyo branch in August 1926. |
| 1927-09 |
Mitsui Trust opened Osaka branch in September 1927. |
| 1928-12 |
Fukuoka branch of Sumitomo Trust opened in December 1928. |
| 2017 |
Second Founding 2017–2019 |
