13.    Concentrations of Risk

The Company’s revenues are concentrated in a small group of customers with some individually having more than 10% of total revenues.  Revenues from three customers that exceeded 10% of total revenues for the nine months ended September 30, 2020 were 13%,  26% and 45%.  Accounts receivable from there same three customers were 0%, 42% and 37%, respectively, of the total accounts receivable as of September 30, 2020. 

For the nine months ended September 30, 2019, the Company's revenues were concentrated in a small group of customers with some individually having more that 10% of total revenues. Revenues from three customers that exceeded 10% of total revenues for the nine months ended September 30, 2019 were 41%,  19% and 16%. Accounts receivable from these same three customers were 34%,  46% and 0%, respectively, of the total accounts receivable as of September 30, 2019.

The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash. Cash balances are maintained principally at major U.S. financial institutions and are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to regulatory limits. From time to time, cash balances may exceed the FDIC insurance limit. The Company has not experienced any credit losses associated with its cash balances in the past.