under a term loan, $143.8 million of outstanding Notes, and $29.3 million in other debt. Our debt agreements bear interest at rates between 2.3% and 6.75%.
Our primary cash needs are for working capital. Our maintenance capital expenditures have typically been less than 1.0% of net sales, but we may make additional capital expenditures as necessary to support our growth, such as the investment in additional veterinary clinics. Our primary working capital requirements are to carry inventory and receivable levels necessary to support our increasing net sales. Fluctuations in working capital are primarily driven by the timing of new product launches and seasonal retailer demand. As of June 30, 2020 and December 31, 2019, we had working capital (current assets less current liabilities) of $257.9 million and $112.4 million, respectively.
Additionally, the Company acquired the U.S. rights to Capstar® and CapAction® and related assets (the “Acquisition”) from Elanco, US Inc. for $95 million, plus the cost of certain outstanding finished goods inventory in saleable condition. The Acquisition closed on July 31, 2020 and was financed using cash from the sale of the Notes in May 2020.
We believe that our operating cash flow, cash on hand, and debt proceeds from our borrowings under our credit facility will be adequate to meet our operating, investing, and financing needs for the foreseeable future. To the extent additional funds are necessary to meet long-term liquidity needs as we continue to execute our business strategy, we anticipate that they will be obtained through the incurrence of additional indebtedness, additional equity financings or a combination of these potential sources of funds, although we can provide no assurance that these sources of funding will be available on reasonable terms.
Cash Flows
Cash used in Operating Activities
Net cash used in operating activities was $42.4 million for the six months ended June 30, 2020, compared to cash used in operating activities of $18.1 million for the six months ended June 30, 2019. The change in operating cash flows primarily reflects lower earnings and a significant expansion in working capital. Working capital changes are driven by increased inventory and accounts receivable on the seasonality of the business, growing sales, offset somewhat by growth in accounts payable. Net changes in assets and liabilities accounted for $52.7 million in cash used in operating activities for the six months ended June 30, 2020 compared to $37.9 million of cash used in operating activities for the six months ended June 30, 2019.
Cash used in Investing Activities
Net cash used in investing activities was $10.0 million for the six months ended June 30, 2020, compared to $1.7 million for the six months ended June 30, 2019. The increase in net cash used in investing activities is a result of the continued wellness center rollout initiative as well as the start of construction on a new corporate headquarters.
Cash provided by Financing Activities
Net cash provided by financing activities was $142.4 million for the six months ended June 30, 2020, compared to $10.1 million in net cash used by financing activities for the six months ended June 30, 2019. The change in cash provided by financing activities is primarily driven by the Company’s utilization of its revolving credit facility to fund working capital expansion due to seasonality and the issuance of Convertible Notes. During the six months ended June 30, 2020, we received $137.9 million of proceeds from the issuance of 4.0% Convertible Senior Notes Due 2026 (the “Notes”), net of issuance costs, paid $14.8 million for privately negotiated convertible note hedge transactions (“Capped Call”).
Description of Indebtedness
Convertible Notes
On May 19, 2020, the Company issued $143.8 million in aggregate principal amount of 4.00% Convertible Senior Notes pursuant to the indenture (the “Indenture”), dated as of May 19, 2020. The total net proceeds from the Notes offering, after deducting debt issuance costs paid or payable by us, was $137.9 million. The Notes accrue interest at a rate of 4.00% per annum, payable semi-annually in arrears on June 1 and December 1 of each year, beginning on December 1,