The proposal behind the headline
On November 12, 2021, Toshiba's strategic review committee explained a plan to separate the group into three standalone companies. The board presented the proposal as a way to clarify business focus and improve shareholder value. It followed a review of strategic alternatives, including discussions concerning outside investment.
The important word is plan. A board announcement can set out a desired structure while approvals, implementation steps and alternatives remain unresolved. It is not equivalent to three newly independent companies already beginning trading.
Source [1]How to avoid turning a proposal into an outcome
Toshiba's February 2022 shareholder materials referred back to the November proposal and discussed continuing review of alternatives. Those documents illustrate why a restructuring story needs later filings before it can be described as completed.
This page explains the original three-company announcement without asserting that it became Toshiba's eventual structure. For any current investment or ownership question, use the company's latest formal disclosures. McDonald's Russia exit offers a related example of a corporate plan whose announcement, transaction terms and later execution require separate evidence.
Source [2]