Related Party Disclosures	12 Months Ended
Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Disclosures	11. Related Party Disclosures StockCross StockCross and the Company are under common ownership and StockCross serves as one of the two clearing brokers for the Company. StockCross has a clearing agreement with MSCO in which StockCross passes through all revenue and charges MSCO for related clearing expenses. Outside of the clearing agreement, MSCO has an expense sharing agreement with StockCross for its Beverly Hills office. In addition, StockCross pays some of the vendors for miscellaneous expenses which it passes through to MSCO. Lastly, as of December 31, 2018, MSCO had receivables from StockCross totaling approximately $1.3 million consisting of financing for inventory positions, the net monthly clearing fees StockCross owes MSCO, and a clearing deposit. As of December 31, 2017, MSCO had a receivable from StockCross totaling $283,000. KCA KCA is an affiliate of the Company and StockCross. To gain efficiencies and economies of scale with billing and administrative functions, KCA serves as a paymaster for the Company and StockCross for compensation and benefits expenses, the entirety of which KCA passes through to the Company and StockCross proportionally. In addition, KCA has purchased the naming rights for the Company for the Company to use. PWC PWC brokers the insurance policies for related parties. Revenue for PWC from related parties totaled $28,000 for the year ended December 31, 2018. Scilent Networks LLC (Scilent Networks) Scilent Networks is a technology wholesaler owned by a Siebert executive that buys technology and related services on behalf of the Company at a reduced cost and then passes through the cost to the Company. Total expenses related to Scilent Networks totaled $133,000 and $112,000 for the years ended December 31, 2018 and 2017, respectively.

11. Related Party Disclosures

StockCross

StockCross and the Company are under common ownership and StockCross serves as one of the two clearing brokers for the Company. StockCross has a clearing agreement with MSCO in which StockCross passes through all revenue and charges MSCO for related clearing expenses. Outside of the clearing agreement, MSCO has an expense sharing agreement with StockCross for its Beverly Hills office. In addition, StockCross pays some of the vendors for miscellaneous expenses which it passes through to MSCO. Lastly, as of December 31, 2018, MSCO had receivables from StockCross totaling approximately $1.3 million consisting of financing for inventory positions, the net monthly clearing fees StockCross owes MSCO, and a clearing deposit. As of December 31, 2017, MSCO had a receivable from StockCross totaling $283,000.

KCA

KCA is an affiliate of the Company and StockCross. To gain efficiencies and economies of scale with billing and administrative functions, KCA serves as a paymaster for the Company and StockCross for compensation and benefits expenses, the entirety of which KCA passes through to the Company and StockCross proportionally. In addition, KCA has purchased the naming rights for the Company for the Company to use.

PWC

PWC brokers the insurance policies for related parties. Revenue for PWC from related parties totaled $28,000 for the year ended December 31, 2018.

Scilent Networks LLC (Scilent Networks)

Scilent Networks is a technology wholesaler owned by a Siebert executive that buys technology and related services on behalf of the Company at a reduced cost and then passes through the cost to the Company. Total expenses related to Scilent Networks totaled $133,000 and $112,000 for the years ended December 31, 2018 and 2017, respectively.