in Mobius Imagine, LLC, partially offset by a loss our warrants for preferred stock on RedSeal, Inc. The net realized gain on investments of $59,792 for the year ended December 31, 2018 was primarily due to the gain on our warrants for preferred stock of Placecast, Inc.
Net Change in Unrealized Appreciation (Depreciation) on Investments
Net change in unrealized appreciation on investments of $14,257,593 for the year ended December 31, 2020 was primarily due to increases in the fair value of our senior secured loans to Aria Systems, Inc. and our warrants for preferred stock or common stock of Ouster, Inc., MTBC, Inc., and Aspen Group Inc. This increase was offset by the decreases in the fair value of senior secured loans to Circadence Corporation and Pivot3, Inc., and our preferred stock in MTBC, Inc. Net change in unrealized depreciation on investments of $9,416,462 for the year ended December 31, 2019 was primarily due to increases in the fair value of our senior secured loans to eSilicon Corporation and Realwear, Inc., our preferred stock in Aria Systems, Inc. and our warrants for preferred stock of Aria Systems, Inc. and eSilicon Corporation. This increase was offset by the decreased in the fair value of senior secured loans to Aginity, Inc., CareCloud Corporation, and Mojix Inc., and our warrants for common or preferred stock of All Clear ID, Inc., Mojix Inc. and zSpace, Inc. The net change in unrealized depreciation on investments of $8,693 for the year ended December 31, 2018 was primarily due to increases in the fair value of our senior secured loans to AllClear ID, Inc. and eSilicon Corporation, our preferred stock in Aria Systems, Inc. and our warrants for preferred stock of Aria Systems, Inc., eSilicon Corporation, Mojix Inc. and ShareThis, Inc. This increase was partially offset by decreases in the fair value of our senior secured loans to Aginity, Inc., Aria Systems, Inc., CareCloud Corporation, and Mojix Inc., and our warrants for common or preferred stock of AllClear ID, Inc., Aspen Group Inc., Mojix Inc. and SendtoNews Video, Inc.
The COVID-19 pandemic and its resultant impact on economic activity and capital market volatility has impacted and may continue to have an impact on the fair market values of our investments. As of December 31, 2020, numerous variables used in the valuation process reflected the impact of the COVID-19 pandemic, such as market comparables, market volatility, discount rates and credit spreads; however, the dynamic nature of the COVID-19 pandemic and ability of portfolio companies to assess its impact on future performance may not be fully incorporated into our assumptions. As a result, the fair market values of our portfolio investments may be negatively impacted after December 31, 2020 by circumstances and events that are not yet known, including the complete or continuing impact of the COVID-19 pandemic and the resulting measures taken in response thereto. Our valuation process carefully considers the impact of the COVID-19 pandemic-related uncertainties in the various inputs utilized in the determination of the fair market value of investments.
Net Increase in Net Assets Resulting from Operations
We had a net increase in net assets resulting from operations of $46,979,900 for the year ended December 31, 2020, as compared to a net increase in net assets resulting from operations of $27,646,400 and $11,757,516 for the years ended December 31, 2019 and December 31, 2018, respectively. The net increase in net assets resulting from operations for the year ended December 31, 2020 from the year ended December 31, 2019 is attributable to increases in the fair value of our senior secured loans to Aria Systems, Inc. and our warrants for preferred stock or common stock of Ouster, Inc., MTBC, Inc., and Aspen Group Inc. The net increase in net assets resulting from operations for the year ended December 31, 2019 from the year ended December 31, 2018 is attributable to increased interest income earned on our portfolio investments and the gain on our warrants for preferred stock or units on Drawbridge, Inc. and Mobius Imagine, LLC. The net increase in net assets resulting from operations for the year ended December 31, 2018 from the year ended December 31, 2017 is attributable to increased interest income earned on our portfolio investments and the gain on our warrants for preferred stock of Placecast, Inc.
Financial Condition, Liquidity and Capital Resources
We generate cash primarily from the net proceeds of the offering of our securities and cash flows from our operations, including investment sales and repayments as well as income earned on investments and cash equivalents. We may also fund a portion of our investments through borrowings under the Credit Agreement (discussed below). We expect that we may also generate cash from any financing arrangements we may enter into in the future and any future offerings of our equity or debt securities. We may fund a portion of our investments through borrowings from banks and issuances of senior securities. Our primary use of funds is to make investments in eligible portfolio companies, pay our operating expenses and make distributions to holders of our common stock.
During the year ended December 31, 2020, cash and cash equivalents decreased to $14,886,246, from $45,799,672 as of December 31, 2019. This decrease was primarily the result of the purchase of investments in portfolio companies for $272,532,493 and