Investments and Fair Value of Financial Assets and Liabilities
 6 Months Ended
Jun. 30, 2019
Investments and Fair Value of Financial Assets and Liabilities  
Investments and Fair Value of Financial Assets and Liabilities

3. Investments and Fair Value of Financial Assets and Liabilities

Investments by security type consisted of the following (in thousands):

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

June 30, 2019

 

 

Amortized Cost

 

Gross
Unrealized
Gains

 

Gross
Unrealized
Losses

 

Fair Value

U.S. treasury notes (due within one year)

 

$

188,030

 

$

268

 

$

 —

 

$

188,298

U.S. government agency bonds (due within one year)

 

 

32,926

 

 

22

 

 

 —

 

 

32,948

 

 

$

220,956

 

$

290

 

$

 —

 

$

221,246

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

December 31, 2018

 

 

Amortized Cost

 

Gross
Unrealized
Gains

 

Gross
Unrealized
Losses

 

Fair Value

U.S. treasury notes (due within one year)

 

$

79,312

 

$

 —

 

$

(26)

 

$

79,286

U.S. government agency bonds (due within one year)

 

 

17,704

 

 

 —

 

 

(3)

 

 

17,701

 

 

$

97,016

 

$

 —

 

$

(29)

 

$

96,987

 

The following tables present the Company’s fair value hierarchy for its assets and liabilities, which are measured at fair value on a recurring basis (in thousands):

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fair value measurements at June 30, 2019 using:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    

Level 1

    

Level 2

    

Level 3

    

Total

Assets:

 

 

  

 

 

  

 

 

  

 

 

  

Cash equivalents:

 

 

  

 

 

  

 

 

  

 

 

  

Money market funds

 

$

141,084

 

$

 —

 

$

 —

 

$

141,084

Investments:

 

 

 

 

 

 

 

 

 

 

 

  

U.S. government agency bonds

 

 

 —

 

 

32,948

 

 

 —

 

 

32,948

U.S. treasury notes

 

 

 —

 

 

137,150

 

 

 —

 

 

137,150

U.S. treasury bills

 

 

 —

 

 

51,148

 

 

 —

 

 

51,148

 

 

$

141,084

 

$

221,246

 

$

 —

 

$

362,330

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fair value measurements at December 31, 2018 using:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    

Level 1 

    

Level 2 

    

Level 3

    

Total 

Assets:

 

 

  

 

 

  

 

 

  

 

 

  

Cash equivalents:

 

 

  

 

 

  

 

 

  

 

 

  

Money market funds

 

$

282,160

 

$

 —

 

$

 —

 

$

282,160

U.S. treasury bills

 

 

 —

 

 

24,904

 

 

 —

 

 

24,904

Investments:

 

 

  

 

 

  

 

 

  

 

 

  

U.S. government agency bonds

 

 

 —

 

 

17,701

 

 

 —

 

 

17,701

U.S. treasury notes

 

 

 —

 

 

79,286

 

 

 —

 

 

79,286

 

 

$

282,160

 

$

121,891

 

$

 —

 

$

404,051

 

U.S. government money market funds were valued by the Company based on quoted market prices, which represent a Level 1 measurement within the fair value hierarchy. U.S. treasury notes and U.S. government agency bonds were valued by the Company using quoted prices in active markets for similar securities, which represent a Level 2 measurement within the fair value hierarchy. There have been no changes to the valuation methods during the six months ended June 30, 2019. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers between Level 1, Level 2 or Level 3 during the six months ended June 30, 2019.