For the nine months ended September 30, 2022, net cash used in operating activities was approximately $5,610,000, which consisted of a net loss of approximately $8,086,000 offset by non-cash charges of approximately $1,829,000, which included $825,804 related to amortization of internally developed software, $633,475 in stock-based compensation, $340,858 in bad debt expense, $13,587 related to depreciation and amortization of property and equipment, $9,207 of amortization of debt issuance costs on the Term Loan, and $6,250 of proceeds from issuance of common stock in exchange for services. Total changes in assets and liabilities of approximately $647,000 were attributable to a $876,779 decrease in accounts receivable-unbilled, a $427,798 decrease in accounts receivable, and a $135,057 increase in accounts payable, offset by a $654,745 decrease in deferred revenue, a $124,240 decrease in accrued expenses, and a $14,520 increase in prepaid expenses and other current assets.
Investing Activities
Net cash used in investing activities was approximately $6,505,000 and $1,549,000 for the nine months ended September 30, 2023 and 2022, respectively. Net cash used in investing activities for the nine months ended September 30, 2023 consisted of $10,143,156 of purchases of available-for-sale securities, $3,692,706 of capitalization of internally developed software and other non-current assets, and $19,478 of purchases of property and equipment, which were offset by $7,350,000 of proceeds from sale and maturities of available-for-sale securities. Net cash used in investing activities for the nine months ended September 30, 2022 consisted of $1,549,281 of capitalization of internally developed software.
Financing Activities
Net cash provided by financing activities was approximately $71,000 and $78,000 for the nine months ended September 30, 2023 and 2022, respectively. Net cash provided by financing activities for the nine months ended September 30, 2023 consisted of $70,889 received from the exercise of stock options. Net cash provided by financing activities for the nine months ended September 30, 2022 consisted of $78,387 received from the exercise of stock options.
Effects of Inflation and Supply Chain Shortages
Our operations are heavily reliant on specimen availability, and as a result, we often receive more requests than we can fulfill. While the Company is subject to these types of supply chain constraints that are specific to the specimen industry, we have not been materially affected by the more common supply chain issues currently affecting the economy, specifically surrounding transportation, except for an increase in our shipping costs. Shipping costs increased approximately $126,000, or 36%, from approximately $352,000 to $478,000 period over period during the nine months ended September 30, 2023. Due to the small size of the packages that we ship, our carriers were able to continue making timely deliveries during the nine months ended September 30, 2023.
We have experienced negative effects of inflation in certain areas of our business due to the high rates of inflation in the world’s current economy. This inflation is affecting employee salaries, which account for a significant portion of our operating costs. Additionally, the costs of supplies have been affected by inflation; however, these costs are not significant to the Company’s results.
Inflation has not had a significant impact on the cost of specimens due to our long-term contracts maintained with vendors, which include revenue sharing plans.
Non-GAAP Financial Measure
To supplement our unaudited condensed financial statements, which are prepared and presented in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”), we use adjusted earnings before interest, taxes, depreciation, and amortization (“Adjusted EBITDA”), a non-GAAP financial measure, to understand and evaluate our core operating performance. This non-GAAP financial measure, which may be different than similarly titled measures used by other companies, is presented to enhance investors’ overall understanding of our financial performance and should not be considered a substitute for, or superior to, the financial information prepared and presented in accordance with GAAP.
We define our non-GAAP financial measure of Adjusted EBITDA as net loss, excluding income tax benefit, depreciation and amortization, non-cash impact of severance accruals, stock-based compensation expense and interest expense.