21. Related Party Disclosures

KCA

Kennedy Cabot Acquisition, LLC (“KCA”) owns a license from the Muriel Siebert Estate / Foundation to use the names “Muriel Siebert & Co., LLC.” and “Siebert” within business activities, which expires in 2026. The Company did not pass through any costs for the use of these names for either the three or six months ended June 30, 2026 and 2025.

KCA has earned no profit for providing any services to the Company as KCA passed through any revenue or expenses to the Company’s subsidiaries for both the three or six months ended June 30, 2026 and 2025.

PW

PW brokers the insurance policies for related parties. Revenue for PW from related parties was $5,000 and $56,000 for the three months ended June 30, 2026 and 2025, respectively. Revenue for PW from related parties was $28,000 and $62,000 for the six months ended June 30, 2026 and 2025, respectively.

Gloria E. Gebbia, John J. Gebbia, and Gebbia Family Members

The three sons of Gloria E. Gebbia and John J. Gebbia hold executive positions within the Company’s subsidiaries and their compensation was in aggregate $1,539,000 and $987,000 for the three months ended June 30, 2026 and 2025, respectively. The compensation for the sons of Gloria E. Gebbia and John J. Gebbia was in aggregate $2,567,000 and $1,859,000 for the six months ended June 30, 2026 and 2025, respectively. Part of their compensation includes payments related to key revenue streams.

On May 22, 2023, Gloria E. Gebbia issued a warrant to BCW Securities LLC, a Delaware limited liability company, to purchase 403,780 shares of common stock of the Company held by Gloria E. Gebbia at an exercise price of $2.15 per share. Refer to Note 6 - Kakaopay Transaction in the Company’s 2025 Form 10-K for further information.

Gebbia Sullivan County Land Trust

The Company operated a month-to-month lease agreement for its branch office in Omaha, Nebraska with the Gebbia Sullivan County Land Trust, the trustee of which is a member of the Gebbia Family. For the three months ended June 30, 2026 and 2025, rent expense was $0 and $15,000, respectively, for this branch office. For the six months ended June 30, 2026 and 2025, rent expense was $10,000 and $30,000, respectively, for this branch office. In March 2026, the Gebbia Sullivan County Land Trust terminated the lease agreement with the Company.

EWB Credit Agreement

On August 15, 2024, the Company entered into the EWB Credit Agreement with East West Bank whereby John J. Gebbia and Gloria E. Gebbia, along with the John and Gloria Living Trust, guarantee the Company’s obligations under the EWB Credit Agreement. Refer to Note 18 - Commitments, Contingencies, and Other for more information.

Kakaopay and Affiliates

On April 27, 2023, the Company entered into a Stock Purchase Agreement with Kakaopay Corporation (“Kakaopay”), pursuant to which the Company issued to Kakaopay 8,075,607 shares of the Company’s common stock at a per share price of $2.15. Refer to Note 6 – Kakaopay Transaction in the Company’s 2025 Form 10-K for further information.

MSCO entered into an agreement whereby it would provide an omnibus trading account for Kakaopay’s subsidiary, Kakaopay Securities Corp., and provide trade execution services to Kakaopay Securities Corp., subject to compliance with applicable U.S. laws, rules and regulations. The Company has earned approximately $495,000 and $672,000, during the three and six months ended June 30, 2026, respectively, in relation to this agreement.

RISE

MSCO and RISE have a clearing agreement whereby RISE introduces clients to MSCO. As part of the agreement, RISE deposited a clearing fund escrow deposit of $50,000 to MSCO, and had excess cash of approximately $1.0 and $1.1 million in its brokerage account at MSCO as of June 30, 2026 and December 31 2025, respectively. The resulting asset of RISE and liability of MSCO is eliminated in consolidation. There was an interest expense of $8,000 and $8,000 related to this clearing agreement for the three months ended June, 2026 and 2025 respectively. There was an interest expense of $16,000 and $17,000 related to this clearing agreement for the six months ended June, 2026 and 2025 respectively.

On October 28, 2025, the Company purchased the remaining 32% interest in RISE for $3.7 million from members of the Gebbia family and employees of the Company. Upon completion of the transaction, RISE became a wholly-owned subsidiary of Siebert. Refer to Note 5 - RISE in the Company’s 2025 Form 10-K for further information.