It's called a reverse triangular merger or merger sub
A commonly used merger structure is the “reverse triangular merger.” In a reverse triangular merger, the acquiring company will form a wholly-owned subsidiary company (a “merger sub”). When the merger transaction closes, the merger sub will be merged with and into the target company, with the target company surviving as a wholly-owned subsidiary of the acquiring company. The stockholders of the target company will receive the consideration offered by the acquiring company (generally cash, stock of the acquiring company, or some combination of each) as payment for “selling” their equity in the target company.
Benefits of a Reverse Triangular Merger A reverse triangular merger is attractive when the seller’s continued existence is needed for reasons other than tax benefits, such as rights relating to franchising, leasing or contracts, or specific licenses that may be held and owned solely by the seller.
Target can transfer all or a part of its assets to a subsidiary controlled by Target and Acquiring can transfer its Target stock to a subsidiary controlled by Acquiring. https://pmstax.com/acqbasic/a2Erg.shtml