4. FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

May 31, 2019

Fair Value Disclosures [Abstract]

Fair value by hierarchy

    The following table summarizes the Company’s financial assets measured at fair value on a recurring basis as of May 31, 2019 (in thousands):

	Balance as of
	May 31, 2019		Level 1		Level 2		Level 3
Money market funds	$	3,017	$	3,017	$	—	$	—
Assets	$	3,017	$	3,017	$	—	$	—

    The following table summarizes the Company’s financial assets measured at fair value on a recurring basis as of May 31, 2018 (in thousands):

	Balance as of
	May 31, 2018		Level 1		Level 2		Level 3
Money market funds	$	7,813	$	7,813	$	—	$	—
U.S. Treasury securities		5,983		5,983		—		—
Assets	$	13,796	$	13,796	$	—	$	—