5.    Cash, cash equivalents and investments

As of  September 30, 2023 and December 31, 2022, cash, cash equivalents and investments comprised funds in depository, money market accounts, U.S. and foreign treasury securities, asset-backed securities and corporate bonds. The following table presents the cash equivalents and investments carried at fair value in accordance with the hierarchy defined in Note 2 at September 30, 2023 and December 31, 2022.

Cash equivalents and marketable securities have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income and market-based approaches and observable market inputs to determine value. The Company validates the prices provided by its third-party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources, as needed. After completing its validation procedures, the Company did not adjust any fair value measurements provided by the pricing services as of September 30, 2023.

Investments at September 30, 2023 consisted of the following (in thousands):

The Company recorded no realized gains or losses and $0.1 million in realized losses from the maturity of available-for-sale securities during the three and nine months ended September 30, 2023, respectively, and recorded $0.2 million and $0.3 million in realized gains from the maturity of available-for-sale securities during the three and nine months ended September 30, 2022, respectively.

As of September 30, 2023, there were no investments with a fair value that was significantly lower than the amortized cost basis or any investments that had been in an unrealized loss position for a significant period.