Assignment history — US Patent 11581322

Inventors

Mei Lan GUO (Yangtze Memory Technologies Co Ltd)
Yushi Hu (Yangtze Memory Technologies Co Ltd)
Ji Xia (Yangtze Memory Technologies Co Ltd)
Hongbin Zhu (Yangtze Memory Technologies Co Ltd)

Original assignee

Yangtze Memory Technologies Co Ltd (YMTC) is an integrated device manufacturer (IDM) specializing in the design, production, and sale of 3D NAND flash memory chips. They ship products such as 3D NAND wafers, dies, embedded memory solutions, consumer and enterprise solid-state drives (SSDs) for applications including mobile devices, PCs, and data centers. YMTC has successfully mass-produced 32-layer, 64-layer, 128-layer, and 232-layer 3D NAND chips. As of 2026, YMTC is an operating company with rapid revenue growth and plans for an initial public offering (IPO). They are also actively working with Chinese semiconductor equipment manufacturers due to U.S. trade sanctions, but still rely on Western manufacturers.

Assignment timeline

Based on a search of the USPTO Assignment Center for patent US11581322, there are no recorded assignments for this patent after its initial assignment to Yangtze Memory Technologies Co Ltd. The Google Patents legal events also indicate that the application was assigned to Yangtze Memory Technologies Co Ltd on 2020-11-21, which is the filing date of the application. This suggests that the patent has remained with its original assignee since its inception.

Timeline diagram

timeline
    title Ownership of US 11581322
    2018 : Priority date
    2020 : Application filed
         : Assigned to Yangtze Memory Technologies Co Ltd
    2023 : Patent Issued

NPE / troll-pattern signals

Shell-entity transfer — Not present. The patent remains with Yangtze Memory Technologies Co Ltd, an operating company that designs, produces, and sells 3D NAND flash memory. There is no evidence of transfer to a licensing-only LLC.
Known asserter in the chain — Not present. Yangtze Memory Technologies Co Ltd is not listed as a known NPE or patent asserter by public lists.
Repeat correspondent across the chain — Not present. There are no recorded assignments in the USPTO Assignment Center for this patent beyond the initial assignment to the original assignee.
Cascading transfers — Not present. There are no recorded assignments in the USPTO Assignment Center for this patent beyond the initial assignment to the original assignee.
Pre-litigation transfer — Unclear. While the patent has litigation associated with it (multiple US cases filed in California Northern and Eastern District Courts, and a PTAB case IPR2025-00191), there are no recorded assignments immediately preceding these litigations [cite: https://patents.google.com/patent/US11581322/en]. Without assignment records, it's impossible to confirm a pre-litigation transfer.
Bankruptcy fire-sale — Not present. Yangtze Memory Technologies Co Ltd is an active, operating company.
Privateering — Not present. There is no evidence of YMTC transferring the patent to an NPE for assertion on their behalf.
Defensive aggregator (anti-NPE) — Not present. The patent is held by Yangtze Memory Technologies Co Ltd, an operating company.

Verdict

Operating-company assertion
The patent US11581322 remains with its original assignee, Yangtze Memory Technologies Co Ltd, which is an active integrated device manufacturer of 3D NAND flash memory products. The Google Patents page for US11581322 indicates ongoing litigation (multiple US district court cases and a PTAB IPR), suggesting the operating company is asserting its patent rights.

Verification: https://assignmentcenter.uspto.gov/ (Search by patent number: 11581322)