Balance Sheet Accounts

Cash and Cash Equivalents—As of December 31, 2018 and 2017, our cash equivalents consisted of money market accounts that invested in U.S. government-sponsored enterprise bonds and discount notes, U.S. government treasury bills and notes and repurchase agreements collateralized by U.S. government obligations. As of December 31, 2018 and 2017, our cash equivalents carried no unrealized gains or losses and we did not realize any significant gains or losses on sales of cash equivalents during the years ended December 31, 2018 and 2017.

As of December 31, 2018 and 2017, our cash and cash equivalent balances were invested as follows (in thousands):



	December 31, 2018		December 31, 2017
Cash	$	12,766	$	5,098
Money market funds	323		35,195
Total cash and cash equivalents	$	13,089	$	40,293

Concentration of Credit Risk—Our financial instruments that are exposed to concentrations of credit risk principally consist of cash, cash equivalents and total accounts receivable (which includes commissions receivable). We invest our cash and cash equivalents with major banks and financial institutions and, at times, such investments are in excess of federally insured limits. We also have deposits with major banks in China that are denominated in both U.S. dollars and Chinese Yuan Renminbi and are not insured by the U.S. federal government.

We do not require collateral or other security for our total accounts receivable. As of December 31, 2018, three customers represented 19%, 19% and 19%, respectively, for a combined total of 57% of our $349.5 million total outstanding accounts receivable balance. As of December 31, 2017, three customers represented 19%, 18% and 18%, respectively, or a combined total of 55%, of our $280.9 million total outstanding accounts receivable balance. No other customers represented 10% or more of our total accounts receivable at either December 31, 2018 or 2017. We believe the potential for collection issues with any of our customers was minimal as of December 31, 2018. Accordingly, our estimate for uncollectible amounts at December 31, 2018 was immaterial.

Accounts Receivable—As of December 31, 2018 and 2017, our total accounts receivable consisted of the following (in thousands):



	December 31, 2018		December 31, 2017
Commissions receivable - current	$	134,190	$	109,666
Commissions receivable - non-current	211,668		169,751
Accounts receivable	3,601		1,475
Total accounts receivable	$	349,459	$	280,892

The commissions receivable balance as of December 31, 2018 and 2017, primarily relates to Medicare Advantage and Medicare Part D plans sold during the fourth quarters of 2018 and 2017 with effective dates in 2019 and 2018, respectively.

Prepaid Expenses and Other Current Assets—As of December 31, 2018 and 2017, prepaid expenses and other current assets consisted of the following (in thousands):



	December 31, 2018		December 31, 2017
Prepaid maintenance contracts	$	1,937	$	1,944
Equity issuance costs	294		—
Prepaid insurance	161		490
Prepaid rent	324		311
Income tax receivable	1,108		195
Other current assets	1,464		1,365
Prepaid expenses and other current assets	$	5,288	$	4,305

Property and Equipment—As of December 31, 2018 and 2017, property and equipment consisted of the following (in thousands):



	December 31, 2018			December 31, 2017
Computer equipment and software	$	17,246		$	17,112
Office equipment and furniture	3,319			3,583
Leasehold improvements	6,345			3,156
Property and equipment, gross	26,910			23,851
Less accumulated depreciation and amortization	(19,226		)	(19,146		)
Property and equipment, net	$	7,684		$	4,705

Depreciation and amortization expense related to property and equipment totaled $2.5 million, $2.8 million, and $3.5 million in the years ended December 31, 2018, 2017 and 2016, respectively.

Other Assets—As of December 31, 2018 and 2017, other assets consisted of the following (in thousands):



	December 31, 2018		December 31, 2017
Capitalized software project costs	$	8,308	$	4,481
Security deposits	483		545
Debt issuance costs - non-current	1,099		—
Deferred tax assets	232		232
Income tax receivable	913		1,826
Other assets	241		203
Other assets	$	11,276	$	7,287

Intangible Assets—The carrying amounts, accumulated amortization, net carrying value and weighted average remaining life of our definite-lived amortizable intangible assets, as well as our indefinite-lived intangible trademarks, are presented in the tables below (dollars in thousands, weighted-average useful life is as of December 31, 2018):



	December 31, 2018								December 31, 2017
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Weighted-average remaining useful life	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Technology	$	2,000	$	(611	)	$	1,389	2.1	$	1,700	$	(1,700	)	$	—
Pharmacy and customer relationships	9,500		(8,234		)	1,266		1.3	10,100		(7,884		)	2,216
Trade names, trademarks and website addresses	5,700		(1,220		)	4,480		8.9	907		(697		)	210
Total intangible assets subject to amortization	$	17,200	$	(10,065	)	7,135			$	12,707	$	(10,281	)	$	2,426
Indefinite-lived trademarks and domain names						5,114		Indefinite						5,114
Intangible assets						$	12,249							$	7,540

During the years ended December 31, 2018, 2017 and 2016, amortization expense related to intangible assets totaled $2.1 million, $1.0 million, and $1.0 million, respectively.

As of December 31, 2018, expected amortization expense in future periods is as follows (in thousands):



Years Ending December 31,	Technology		Pharmacy and Customer Relationships		Trade Names, Trademarks and Website Addresses		Total
2019	$	667	$	950	$	570	$	2,187
2020	667		316		510		1,493
2021	55		—		480		535
2022	—		—		480		480
2023	—		—		480		480
Thereafter	—		—		1,960		1,960
Total	$	1,389	$	1,266	$	4,480	$	7,135

Other Current Liabilities—As of December 31, 2018 and 2017, other current liabilities consisted of the following (in thousands):



	December 31, 2018		December 31, 2017
Deferred revenue	$	876	$	385
Taxes payable	224		169
Professional fees	537		1,012
Payable to carriers	418		—
Other accrued expenses	370		442
Total other current liabilities	$	2,425	$	2,008

Non-current Liabilities—As of December 31, 2018 and 2017, non-current liabilities consisted of the following (in thousands):



	December 31, 2018		December 31, 2017
Deferred rent – non-current	$	1,081	$	724
Accrued affiliate commissions - non-current	1,268		1,092
Sublease security deposit	820		—
Other non-current liabilities	170		104
Total non-current liabilities	$	3,339	$	1,920