PTAB challenges

Proceedings overview

US Patent 10931286 has one pending Inter Partes Review (IPR) proceeding, IPR2026-00212. This IPR was filed by Citadel Securities LLC and is currently awaiting an institution decision. Given its pending status, no claims have been invalidated or sustained by the PTAB yet, leaving the patent's defensive posture as currently untested.

IPR2026-00212 — Citadel Securities LLC v. HFT Solutions LLC

• Type: Inter Partes Review
• Filed: 2026-01-09
• Status: Pending. This IPR is in the pre-institution phase, with a decision on institution expected.
• Judge panel: Information not publicly available at this stage of the proceeding.
• Petition grounds: The petition challenged claims 1-20 of U.S. Patent No. 10,931,286 as unpatentable under 35 U.S.C. § 103 (obviousness) in view of various combinations of prior art. The primary prior art references cited include US 2018/0176043 to Badizadegan, US 2018/0227189 to Nielson et al., and US 8,248,095 to Elshoff et al.
• Institution decision: As of 2026-05-28, an institution decision has not yet been rendered. The statutory deadline for the institution decision is generally three months from the patent owner's preliminary response or six months from the petition filing date if no preliminary response is filed.
• Final Written Decision: Not applicable; a Final Written Decision has not been issued as the proceeding is still in the institution phase.
• Settlement / termination: Not applicable; the proceeding is active and no settlement or termination has been publicly recorded.
• Appeal: Not applicable.
• Defensive value: This IPR proceeding has the potential to impact the patentability of claims 1-20. Should the PTAB institute review, and subsequently find claims unpatentable, it would significantly weaken the patent owner's position. Currently, the claims remain patentable until proven otherwise by a Final Written Decision.

Strategic summary

Currently, all claims (1-20) of US10931286 are untested, as the sole IPR proceeding (IPR2026-00212) is still in the pre-institution phase. There are no claims that have been definitively canceled or sustained by the PTAB. This means the patent has not yet been narrowed through IPR.

Regarding the estoppel landscape, 35 U.S.C. § 315(e)(2) will bar Petitioner Citadel Securities LLC (and its privies) from raising any ground they raised or reasonably could have raised in IPR2026-00212 if a Final Written Decision is issued. However, since the IPR is still pending institution, no estoppel has yet attached. For a defendant currently facing assertion, the prior-art grounds raised in IPR2026-00212 (combinations involving Badizadegan, Nielson, and Elshoff) are currently being evaluated by the PTAB. Should institution be denied, these grounds would remain available for other potential challengers not in privity with Citadel. The filing of this IPR by Citadel, a defendant in ongoing district court litigation for this patent, signals a defensive move.

Recommended next steps

Given that IPR2026-00212 is currently pending an institution decision, a key milestone to monitor is the deadline for that decision. If the PTAB decides to institute an IPR, the trial will proceed, with an oral hearing and a Final Written Decision due typically within one year of institution. The public record of the petition, including the specific prior art and arguments against claims 1-20, can be accessed through the USPTO PTAB End-to-End system for IPR2026-00212.