a non-taxing jurisdiction. Income earned in other foreign jurisdictions was not material. We have not been granted any incentivized tax rates and do not operate under any tax holidays in any jurisdiction.
Liquidity and Capital Resources
As of June 30, 2023, we had $346.3 million in cash, cash equivalents and short-term marketable securities, a decrease of $7.5 million from $353.8 million as of December 31, 2022. As of June 30, 2023, we had working capital, defined as current assets less current liabilities, of $486.2 million, an increase of approximately $19.5 million from $466.7 million as of December 31, 2022.
We have a Credit Agreement with Wells Fargo Bank, National Association (the "Credit Agreement") that provides us with a $75.0 million revolving line of credit to use for general corporate purposes with a $20.0 million sub-limit for the issuance of standby and trade letters of credit. The Credit Agreement was amended on June 7, 2021, to provide an alternate borrowing rate as a replacement for LIBOR and extend the termination date from April 30, 2022, to June 7, 2026, with all other terms remaining the same. The Credit Agreement was amended with an effective date of June 28, 2023 to include the Secured Overnight Financing Rates (“SOFR”) as interest rate benchmark rates, with all other terms remaining the same. Our ability to borrow under the revolving line of credit is conditioned upon our compliance with specified covenants, including reporting and financial covenants, primarily a minimum liquidity measure and a debt to earnings ratio, with which we are currently in compliance. The Credit Agreement terminates on June 7, 2026; all advances under the revolving line of credit will become due on such date, or earlier in the event of a default. No advances were outstanding under the agreement as of June 30, 2023.
Cash From Operating Activities
Operating activities generated $22.8 million of cash in the six months ended June 30, 2023. Net income for this period was $21.7 million; we also incurred depreciation, non-cash stock-based compensation expense, amortization of intangibles and amortization premiums on marketable securities of $17.7 million, $14.1 million, $1.1 million, and $0.4 million, respectively. Sources of cash also included a $8.8 million increase in accounts payable (excluding payables related to property and equipment) due to timing of payments. These sources of cash were partially offset by a $14.3 million increase in inventories, a $7.2 million increase in prepaid expenses and other assets primarily due to federal income tax prepayments, a $10.8 million increase in accounts receivable, a $5.4 million decrease in taxes payable and accrued liabilities primarily due to timing of customer rebate payments, and a $2.8 million increase in deferred income taxes.
Operating activities generated $141.4 million of cash in the six months ended June 30, 2022. Net income for this period was $102.1 million; we also incurred depreciation, non-cash stock-based compensation expense, premium amortization on marketable securities and intangibles amortization of $17.2 million, $12.7 million, $1.9 million and $1.3 million, respectively. Sources of cash also included a $13.2 million decrease in accounts receivable due to the timing of collections, a $5.6 million increase in accounts payable (excluding payables related to property and equipment) and a $4.1 million decrease in prepaid expenses and other assets. These sources of cash were partially offset by a $12.0 million increase in inventories and a $2.5 million decrease in taxes payable and accrued liabilities.
Cash From Investing Activities
Our investing activities in the six months ended June 30, 2023 resulted in a $19.4 million net use of cash, primarily consisting of $12.2 million used for purchases of marketable securities net of proceeds from sales and maturities, and $7.2 million used for purchases of property and equipment, primarily production-related machinery and equipment.
Our investing activities in the six months ended June 30, 2022 generated $78.1 million of cash, primarily consisting of $104.8 million from sales and maturities of marketable securities, net of purchases, offset by $27.9 million for purchases of property and equipment, primarily production-related machinery and equipment, partially offset by proceeds of $1.2 million from the sale of an office building.
Cash From Financing Activities
Our financing activities in the six months ended June 30, 2023 resulted in a $24.7 million net use of cash, consisting of $6.0 million for the repurchase of our common stock and $21.8 million for the payment of dividends to stockholders, partially offset by $3.1 million from the issuance of shares through our employee stock purchase plan.