Citadel Securities LLC has filed a counterclaim against HFT Solutions, LLC in a patent infringement lawsuit.

The legal proceedings were launched in December 2024. In its complaint, HFT Solutions asserts that Citadel Securities has directly infringed (literally and equivalently) three patents. These are:

• U.S. Patent No. 10,931,286, titled “Field programmable gate array with external phase-locked loop”.
• U.S. Patent No. 11,128,305, titled “Field programmable gate array with external phase-locked loop,” and
• U.S. Patent No. 11,575,381, titled “Field programmable gate array with external phase-locked loop.”

On January 5, 2026, Citadel Securities submitted an Answer to the Complaint for Patent Infringement filed by HFT. The document, filed with the Illinois Northern District Court, includes a set of defenses as well as a counterclaim against HFT.

Citadel Securities seeks declaratory judgment that each of the Asserted Patents is invalid, and that each of the Asserted Patents is not infringed by Citadel Securities.

In particular, Citadel Securities seeks the following relief from the Court:

1. Find and declare that Citadel Securities has not directly, indirectly, contributorily, by inducement, literally, or under the doctrine of equivalents infringed the ’286 patent;
2. Find and declare that the asserted claims of the ’286 patent are invalid and/or unenforceable;
3. Find and declare that Citadel Securities has not directly, indirectly, contributorily, by inducement, literally, or under the doctrine of equivalents infringed the ’305 patent;
4. Find and declare that the asserted claims of the ’305 patent are invalid and/or unenforceable;
5. Find and declare that Citadel Securities has not directly, indirectly, contributorily, by inducement, literally, or under the doctrine of equivalents infringed the ’381 patent;
6. Find and declare that the asserted claims of the ’381 patent are invalid and/or unenforceable;
7. Deny all relief requested by Plaintiff;
8. Dismiss this action in its entirety with prejudice;
9. Grant Citadel Securities its costs (including expert fees), disbursements, and reasonable attorneys’ fees in this action, pursuant to 35 U.S.C. § 285 and 28 U.S.C. § 1920; and
10. Grant all other and further relief as the Court may deem just and proper.