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Short-Term Investments | 9 Months Ended
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Sep. 30, 2023
Short-Term Investments |
Short-Term Investments | 4.Short-Term Investments The following table summarizes the short-term investments held at September 30, 2023 and December 31, 2022 (in thousands): ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | ​ | ​ |  | Gross Unrealized |  | Gross Unrealized |  | ​ | ​
​ | ​ | Amortized Cost | ​ | Gains | ​ | Losses | ​ | Fair Value
September 30, 2023 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Reverse repurchase agreements | ​ | $ | 69,000 | ​ | $ | — | ​ | $ | — | ​ | $ | 69,000
Total | ​ | $ | 69,000 | ​ | $ | — | ​ | $ | — | ​ | $ | 69,000
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | Gross Unrealized | ​ | Gross Unrealized | ​ | ​ | ​
​ |  | Amortized Cost |  | Gains |  | Losses |  | Fair Value
December 31, 2022 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Corporate debt securities | ​ | $ | 16,508 | ​ | $ | — | ​ | $ | (63) | ​ | $ | 16,445
Treasury bills | ​ | ​ | 5,983 | ​ | ​ | — | ​ | ​ | (3) | ​ | ​ | 5,980
Yankee securities | ​ | ​ | 2,000 | ​ | ​ | — | ​ | ​ | (1) | ​ | ​ | 1,999
U.S. agency bonds | ​ | ​ | 3,000 | ​ | ​ | — | ​ | ​ | (12) | ​ | ​ | 2,988
Reverse repurchase agreements | ​ | ​ | 178,500 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 178,500
Total | ​ | $ | 205,991 | ​ | $ | — | ​ | $ | (79) | ​ | $ | 205,912
​ The contractual maturities of all short-term investments held at September 30, 2023 and December 31, 2022 were one year or less. There were no short-term investments in an unrealized loss position as of September 30, 2023. There were 16 short-term investments in an unrealized loss position with an aggregate value of $25.6 million as of December 31, 2022. These investments were in a loss position for less than 12 months and the Company considered the loss to be temporary in nature. The Company considered the decline in market value for these securities to be primarily attributable to economic and market conditions. ​ Gross realized gains and losses on the sales of short-term investments are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net, were not material to the Company’s condensed consolidated statements of operations. The cost of investments sold or the amount reclassified out of the accumulated other comprehensive income into other income, net is based on the specific identification method for purposes of recording realized gains and losses. All proceeds in the three and nine month periods ended September 30, 2023 and 2022 related to maturities of underlying investments. The gains on proceeds from maturities of short-term investments were not material to the Company’s condensed consolidated statements of operations for the three and nine months ended September 30, 2023 and 2022.

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