3. Fair Value Measurements

The Company determines the fair value of financial and non-financial assets and liabilities based on the assumptions that market participants would use in pricing the asset or liability in an orderly transaction between market participants at the measurement date. The identification of market participant assumptions provides a basis for determining what inputs are to be used for pricing each asset or liability. A fair value hierarchy has been established which gives precedence to fair value measurements calculated using observable inputs over those using unobservable inputs. This hierarchy prioritized the inputs into three broad levels as follows:

The carrying amounts of financial instruments such as cash and cash equivalents, restricted cash, contributions receivable, prepaid expenses and other current assets, accounts payable, accrued compensation, accrued and other current liabilities approximate the related fair values due to the short maturities of these instruments.

The fair value of the Company’s cost method investment is measured when it is deemed to be other-than- temporarily impaired.

The Company’s financial assets subject to fair value measurements on a recurring basis and the level of inputs used in such measurements were as follows:

 

 

 

The Company estimates the fair value of its money market funds, commercial paper, corporate debt securities, asset-backed securities, and U.S. government debt securities by taking into consideration valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities, issuer credit spreads; benchmark securities; prepayment/default projections based on historical data; and other observable inputs.

There were no transfers within the hierarchy during the three months ended March 31, 2018 and the year ended December 31, 2017.

The grant date fair value of the Company’s common stock has been determined by the Company’s Board of Directors with the assistance of management and an independent third-party valuation specialist. The grant date fair value of the Company’s common stock was determined using valuation methodologies which utilizes certain assumptions including probability weighting of events, volatility, time to liquidation, a risk-free interest rate and an assumption for a discount for lack of marketability (Level 3 inputs). In determining the fair value of the Company’s common stock, the methodologies used to estimate the enterprise value of the Company were performed using methodologies, approaches, and assumptions consistent with the American Institute of Certified Public Accountants Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (“AICPA Accounting and Valuation Guide”).