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Fair Value of Investments | 6 Months Ended
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Jun. 30, 2019
Fair Value of Investments |
Fair Value of Investments |
5. | Fair Value of Investments
The Company has elected the Fair Value Option for all investments in debt securities. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for classification and disclosure of fair value measurements as follows: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company classifies cash equivalents and investments according to the hierarchy of techniques used to determine fair value based on the types of inputs. The following table represents the Company’s fair value hierarchy for its financial assets measured at fair value on a recurring basis as of June 30, 2019: ​ ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | (Level 1) | ​ | (Level 2) | ​ | (Level 3) | ​ | Total
June 30, 2019 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Assets: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Money market funds | ​ | $ | 13,421 | ​ | $ | — | ​ | $ | — | ​ | $ | 13,421
U.S. government securities | ​ | ​ | 14,943 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 14,943
Corporate bonds | ​ | ​ | — | ​ | ​ | 16,089 | ​ | ​ | — | ​ | ​ | 16,089
Commercial paper | ​ | ​ | — | ​ | ​ | 31,977 | ​ | ​ | — | ​ | ​ | 31,977
Asset-backed securities | ​ | ​ | — | ​ | ​ | 15,176 | ​ | ​ | — | ​ | ​ | 15,176
Total assets | ​ | $ | 28,364 | ​ | $ | 63,242 | ​ | $ | — | ​ | $ | 91,606
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | (Level 1) | ​ | (Level 2) | ​ | (Level 3) | ​ | Total
December 31, 2018 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Assets: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Money market funds | ​ | $ | 12,947 | ​ | $ | — | ​ | $ | — | ​ | $ | 12,947
U.S. government securities | ​ | ​ | 15,923 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 15,923
Corporate bonds | ​ | ​ | — | ​ | ​ | 31,495 | ​ | ​ | — | ​ | ​ | 31,495
Commercial paper | ​ | ​ | — | ​ | ​ | 27,869 | ​ | ​ | — | ​ | ​ | 27,869
Asset-backed securities | ​ | ​ | — | ​ | ​ | 17,025 | ​ | ​ | — | ​ | ​ | 17,025
Total assets | ​ | $ | 28,870 | ​ | $ | 76,389 | ​ | $ | — | ​ | $ | 105,259
​ There were no changes in the levels or methodology of the measurement of financial assets or liabilities during the three months ended June 30, 2019. The maturity date of the Company’s investments is less than one year.

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- Definition The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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