4. INVESTMENT SECURITIES, AVAILABLE-FOR-SALE AND FAIR VALUE MEASUREMENTS

Our investment securities, available-for-sale are comprised of corporate and government debt securities. The principal markets for the debt securities are dealer markets which have a high level of price transparency. The market participants for debt securities are typically large money center banks and regional banks, brokers, dealers, pension funds, and other entities with debt investment portfolios.

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the authoritative guidance establishes a three level fair value inputs hierarchy and requires an entity to maximize the use of observable valuation inputs and minimize the use of unobservable inputs. We use market data, assumptions and risks we believe market participants would use in measuring the fair value of the asset or liability, including the risks inherent in the inputs and the valuation techniques. The hierarchy is summarized below.

Level 1 - Quoted prices in active markets for identical assets and liabilities at the measurement date that the reporting entity has the ability to access.

Level 2 - Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.

Level 3 - Unobservable inputs for which there is little or no market data, which requires us to develop our own assumptions, which are significant to the measurement of the fair values.

The valuation inputs hierarchy classification for assets measured at fair value on a recurring basis are summarized below as of June 30, 2022 and December 31, 2021 (in thousands). These tables do not include cash held in our money market savings accounts.

Schedule of Fair Value Hierarchy Assets and Liabilities

Our short-term investments are summarized below as of June 30, 2022 and December 31, 2021 (in thousands).

Schedule of Unrealized Gain or Loss on Short-term Investments

The maturities of the investment securities available-for-sale as of June 30, 2022 and December 31, 2021 are shown below (in thousands):

+Maturity Date of Available-for-sale Securities

The following table summarizes investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for more than 12 months as of June 30, 2022 and December 31, 2021 (in thousands):

Schedule of Unrealized Loss on Investment Securities