Assignment history

Inventors

• Graham Merrett: The sole inventor listed. At the time of the original PCT filing in 2008, no corporate affiliation is listed, suggesting he may have been an independent inventor or acting through a personal holding company.

Original assignee

The entity named on the face of the issued patent is Rembrandt Messaging Technologies LP. However, this entity acquired the patent family via assignment long before this specific patent issued. The ultimate original owner was the inventor, Graham Merrett.

Rembrandt Messaging Technologies LP is a known patent assertion entity and does not appear to have ever shipped a commercial product embodying the claims of the patent. It is a Delaware Limited Partnership, a common structure for non-practicing entities (NPEs). The entity is part of the larger Rembrandt IP Management enforcement program.

Assignment timeline

While no assignments are recorded specifically against the number 11,991,601, the following assignments establishing the chain of title were recorded against its parent application, U.S. Ser. No. 12/452,883. These assignments convey title for the entire patent family.

• 2009-04-16 (executed) / recorded 2009-04-17 — Reel 022728/0879

  • Conveyance: Assignment of assignor's interest
  • Assignor: Graham Merrett
  • Assignee: VISTRA LIMITED (a United Kingdom company)
  • Correspondent: KNOBBE MARTENS OLSON & BEAR LLP, 2040 MAIN ST, 14TH FL, IRVINE, CA 92614. This correspondent reappears below.
  • Context: The inventor transferred his entire interest in the patent family to a corporate entity.

• 2009-04-16 (executed) / recorded 2009-04-17 — Reel 022728/0885

  • Conveyance: Assignment of assignor's interest
  • Assignor: VISTRA LIMITED
  • Assignee: REMBRANDT MESSAGING TECHNOLOGIES, L.P. (a Delaware limited partnership)
  • Correspondent: KNOBBE MARTENS OLSON & BEAR LLP, 2040 MAIN ST, 14TH FL, IRVINE, CA 92614. This is the same correspondent from the immediately preceding assignment.
  • Context: On the exact same day the patent was assigned by the inventor, it was immediately reassigned to the current owner, a known patent-asserter.

• 2014-06-12 (executed) / recorded 2014-06-17 — Reel 032646/0001

  • Conveyance: Nunc Pro Tunc Assignment
  • Assignor: VISTRA LIMITED
  • Assignee: REMBRANDT MESSAGING TECHNOLOGIES, L.P.
  • Correspondent: STERNE, KESSLER, GOLDSTEIN & FOX, P.L.L.C., 1100 NEW YORK AVENUE, N.W., WASHINGTON, DC 20005
  • Context: This "now for then" assignment was filed to correct or reaffirm the 2009 transfer, likely to clean up the chain of title for litigation purposes.

Timeline diagram

timeline
    title Ownership of US 11991601
    2007 : Priority application filed by inventor
    2009 : Assigned to Vistra Limited
         : Re-assigned to Rembrandt Messaging LP
    2014 : Nunc Pro Tunc assignment filed
    2024 : US 11991601 issues
         : Infringement suit filed
    2026 : PTAB IPR challenge filed

NPE / troll-pattern signals

1. Shell-entity transfer — Present. The patent was transferred from the inventor to Vistra Limited (a UK corporate services firm, not a product company) and then immediately to Rembrandt Messaging Technologies LP, a special-purpose entity for monetization (Reels 022728/0879 and 022728/0885).

2. Known asserter in the chain — Present. The current assignee, Rembrandt Messaging Technologies LP, is a well-documented patent assertion entity. The patent data provided confirms active litigation (W.D. Tex. case 1:24-cv-01199) and a pending PTAB challenge (IPR2026-00107).

3. Repeat correspondent across the chain — Present. Both legs of the 2009 transfer (Merrett → Vistra and Vistra → Rembrandt) were recorded on the same day by the same correspondent, KNOBBE MARTENS OLSON & BEAR LLP, indicating a single, coordinated transaction (Reels 022728/0879 and 022728/0885).

4. Cascading transfers — Present. The assignments from the inventor to Vistra and from Vistra to Rembrandt were both executed on the same date, 2009-04-16, representing a textbook cascading transfer to place the patent into an assertion vehicle.

5. Pre-litigation transfer — Not present. The transfers establishing the assertion vehicle occurred in 2009, long before the most recent litigation filed in 2024. However, the entire ownership structure was established for the purpose of assertion from the outset.

6. Bankruptcy fire-sale — Not present. There is no evidence that this patent was acquired out of a bankruptcy proceeding.

7. Privateering — Unclear. There is no public evidence that Vistra Ltd. is an operating company using Rembrandt to assert patents against its competitors. This appears to be a direct acquisition by an NPE.

8. Defensive aggregator (anti-NPE) — Not present. The chain terminates with a known plaintiff, not a defensive entity.

Verdict

NPE — high confidence

The ownership history shows multiple strong signals of NPE activity. The patent was moved from its inventor through a holding company directly into a known assertion entity, Rembrandt Messaging Technologies LP, in a rapid, same-day cascading transfer (Reels 022728/0879 and 022728/0885). The current assignee is a well-documented litigant with no known products, and this patent family is the subject of active litigation.

Verify records at the USPTO Patent Assignment Search page (search by parent application number 12/452,883 to view the relevant chain of title).