According to Envision IP, a law firm specializing in patents, financial institutions in the US make up most of the blockchain patent holders with Bank of America leading the group. The firm identified 1,045 US patents and pending applications related to blockchain and distributed ledger. The search did not include cryptographic and encrypted related patents.
According to Envision IP, "The financial industry dominates the list of the top ten blockchain-related patent holders. For the purposes of this analysis, we grouped patents and published applications together. Leading the list is Bank of America with 43 patents, MasterCard International with 27 patents, FMR LLC (Fidelity) with 14 patents, and TD Bank with 11 patents. Other major financial institutions with blockchain patents include Visa Inc. with 7 patents, American Express with 6 patents, and Nasdaq Inc. with 5 patents.
Interestingly, Nasdaq is not the only exchange which owns blockchain patents, and the Chicago Mercantile Exchange owns two patents in this space. However, these holdings are dwarfed by the leading digital currency exchange Coinbase, Inc., which owns 13 US patents."
From Envision IP: https://tinyurl.com/y7oa8769