The following table shows the Company’s cash, available-for-sale securities, and short-term and long-term investment securities by major security type as of December 31, 2019 and 2018:



	March 31, 2019
				Gross		Gross
	Level			Unrealized		Unrealized
	⁽¹⁾	Fair Value		Holding Gains		Holding Losses			Adjusted Cost
Cash and Cash Equivalents
Cash		$	675,229	$	—	$	—		$	675,229
Money Market Funds	1	3,300,532							3,300,532
Subtotal		3,975,761		—		—			3,975,761
Short-Term Investment Securities ⁽²⁾
Corporate Bonds ⁽⁴⁾	2	35,770,171		—		(7,922		)	35,778,093
Long-Term Investment Securities ⁽³⁾
Corporate Bonds ⁽⁴⁾	2	—		—		—			—
Total		$	39,745,932	$	—	$	(7,922	)	$	39,753,854



	December 31, 2018
				Gross		Gross
	Level			Unrealized		Unrealized
	⁽¹⁾	Fair Value		Holding Gains		Holding Losses			Adjusted Cost
Cash and Cash Equivalents
Cash		$	1,048,272	$	—	$	—		$	1,048,272
Money Market Funds	1	1,338,042							1,338,042
Subtotal		2,386,314		—		—			2,386,314
Short-Term Investment Securities ⁽²⁾
Corporate Bonds ⁽⁴⁾	2	38,731,120		—		(85,321		)	38,816,441
Long-Term Investment Securities ⁽³⁾
Corporate Bonds ⁽⁴⁾	2	—		—		—			—
Total		$	41,117,434	$	—	$	(85,321	)	$	41,202,755

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Notes:

(1) Definition of the three-level fair value hierarchy:


•	Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities


•	Level 2 - Other inputs that are directly or indirectly observable in the markets


•	Level 3 - Inputs that are generally unobservable

(2) Short-term investment securities will mature within 12 months or less, from the applicable reporting date.

(3) Long-term investment securities will mature between 12 and 18 months, from the applicable reporting date.

(4) The premium paid to purchase held-to-maturity investment securities was $80,855 and $286,999 for the three months ended March 31, 2019 and 2018, respectively. The premium paid to purchase held-to-maturity investment securities was $378,681 for the year ended December 31, 2018.