Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

~~Title of each classTrading SymbolName of exchange on which registered~~
~~Common Stock, Par Value $0.01~~ ~~ADTNThe NASDAQ Global Select Market~~

As of May ~~1, 2019,~~7, 2020, the registrant had ~~47,809,152~~47,957,531 shares of common stock, $0.01 par value per share, outstanding.

Item Number		Page Number		Page Number
			Cautionary Note Regarding Forward-Looking Statements	3
			Glossary of Selected Terms	5
	PART I. FINANCIAL INFORMATION		PART I. FINANCIAL INFORMATION

1	Financial Statements:		Financial Statements:
	Consolidated Balance Sheets as of March 31, 2019 – (Unaudited) and December 31, 2018 – (Audited)	3	Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019 – (Unaudited)	6
	Consolidated Statements of Income for the three months ended March 31, 2019 and 2018 – (Unaudited)	4	Condensed Consolidated Statements of Income (Loss) for the three months ended March 31, 2020 and 2019 – (Unaudited)	7
	Consolidated Statements of Comprehensive Loss for the three months ended March 31, 2019 and 2018 – (Unaudited)	5	Condensed Consolidated Statements of Comprehensive Loss for the three months ended March 31, 2020 and 2019 – (Unaudited)	8
	Consolidated Statements of Changes in Stockholders’ Equity for the three months ended March 31, 2019 and 2018	6	Condensed Consolidated Statements of Changes in Stockholders’ Equity for the three months ended March 31, 2020 and 2019 (Unaudited)	9
	Consolidated Statements of Cash Flows for the three months ended March 31, 2019 and 2018 – (Unaudited)	7	Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2020 and 2019 – (Unaudited)	10
	Notes to Consolidated Financial Statements – (Unaudited)	8	Notes to Condensed Consolidated Financial Statements – (Unaudited)	11
2	Management’s Discussion and Analysis of Financial Condition and Results of Operations	29	Management’s Discussion and Analysis of Financial Condition and Results of Operations	33
3	Quantitative and Qualitative Disclosures About Market Risk	37	Quantitative and Qualitative Disclosures About Market Risk	40
4	Controls and Procedures	38	Controls and Procedures	41

	PART II. OTHER INFORMATION		PART II. OTHER INFORMATION
1			Legal Proceedings	42
1A	Risk Factors	39	Risk Factors	42
2	Unregistered Sales of Equity Securities and Use of Proceeds	39	Unregistered Sales of Equity Securities and Use of Proceeds	43
6	Exhibits	40	Exhibits	44

	SIGNATURE	41	SIGNATURE	45

The Private Securities Litigation Reform Act of 1995 provides a safe harbor for forward-looking statements made by or on behalf of ~~ADTRAN.~~ADTRAN, Inc. (“ADTRAN”, the “Company”, “we”, “our” or “us”). ADTRAN and its representatives may from time to time make written or oral forward-looking statements, including statements contained in this report, our other filings with the Securities and Exchange Commission ~~(SEC)~~(the “SEC”) and other communications with our stockholders. Any statement that does not directly relate to a historical or current fact is a forward-looking statement. Generally, the words, “believe”, “expect”, “intend”, “estimate”, “anticipate”, “will”, “may”, “could” and similar expressions identify forward-looking statements. We caution you that any forward-looking statements made by us or on our behalf are subject to uncertainties and other factors that could affect the accuracy of such statements. The following are some of the risks that could affect our financial performance or could cause ~~such statements~~actual results to ~~be wrong.~~ differ materially from those expressed or implied in our forward-looking statements:

The foregoing list of risks is not exclusive. For a more detailed description of the risk factors ~~that could materially affect~~associated with our business, financial condition or operating results is included under “Factors that Could Affect Our Future Results” in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” contained in Item 2 ofsee Part I, ~~of this report. They have also been discussed in~~ Item 1A of ~~Part I in~~ our ~~most recent~~ Annual Report on Form 10-K for the year ended December 31, ~~2018,~~2019, filed with the SEC on February ~~28, 2019 with~~25, 2020 (the “2019 Form 10-K”), as well as the ~~SEC. Though we have attempted to list comprehensively these important~~risk factors weset forth in Part II, Item 1A of this Form 10-Q. We caution investors that other factors may prove to be important in the future in affecting our operating results. New factors emerge from time to time, and it is not possible for us to predict all of these factors, nor can we assess the impact each factor, or a combination of factors, may have on our business.

You are further cautioned not to place undue reliance on these forward-looking statements because they speak only of our views as of the date that the statements were made. We undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

Below are certain acronyms, concepts and defined terms commonly used in our industry and in this Quarterly Report on Form 10-Q, along with their meanings:

March 31,

December 31,

2019

2018

(Unaudited)

(Audited)

ASSETS

Current Assets

Cash and cash equivalents

$
109,119

$
105,504

Short-term investments

31,290

3,246

Accounts receivable, less allowance for doubtful accounts of $82 and $128 at   March 31, 2019 and December 31, 2018, respectively

99,032

99,385

Other receivables

34,583

36,699

Inventory, net

93,609

99,848

Prepaid expenses and other current assets

9,683

10,744

Total Current Assets

377,316

355,426

Property, plant and equipment, net

79,505

80,635

Deferred tax assets, net

36,891

37,187

Goodwill

6,982

7,106

Intangibles, net

31,817

33,183

Other assets

14,885

5,668

Long-term investments

85,227

108,822

Total Assets

$
632,623

$
628,027

LIABILITIES AND STOCKHOLDERS’ EQUITY

Current Liabilities

Accounts payable

$
60,116

$
60,054

Bonds payable

25,600

1,000

Unearned revenue

15,230

17,940

Accrued expenses

14,039

11,746

Accrued wages and benefits

15,105

14,752

Income tax payable, net

11,785

12,518

Total Current Liabilities

141,875

118,010

Non-current unearned revenue

4,514

5,296

Other non-current liabilities

42,687

33,842

Bonds payable

—

24,600

Total Liabilities

189,076

181,748

Commitments and contingencies (see Note 17)

Stockholders’ Equity

Common stock, par value $0.01 per share; 200,000 shares authorized;
      79,652 shares issued and 47,777 shares outstanding at March 31, 2019 and
      79,652 shares issued and 47,751 shares outstanding at December 31, 2018

797

797

Additional paid-in capital

269,529

267,670

Accumulated other comprehensive loss

(14,885
)

(14,416
)
Retained earnings

879,180

883,975

Less treasury stock at cost: 31,875 and 31,901 shares at March 31, 2019 and
   December 31, 2018, respectively

(691,074
)

(691,747
)
Total Stockholders’ Equity

443,547

446,279

Total Liabilities and Stockholders’ Equity

$
632,623

$
628,027

Three Months Ended

March 31,

2019

2018

Sales

Products

$
125,822

$
105,253

Services

17,969

15,553

Total Sales

143,791

120,806

Cost of Sales

Products

70,734

68,612

Services

12,445

12,461

Total Cost of Sales

83,179

81,073

Gross Profit

60,612

39,733

Selling, general and administrative expenses

35,132

33,531

Research and development expenses

31,647

32,849

Operating Loss

(6,167
)

(26,647
)
Interest and dividend income

591

866

Interest expense

(127
)

(132
)
Net investment gain (loss)

5,926

(97
)
Other income (expense), net

855

(57
)
Gain on bargain purchase of a business, net

—

11,322

Income (Loss) Before Provision for Income Taxes

1,078

(14,745
)
(Provision) benefit for income taxes

(308
)

3,931

Net Income (Loss)

$
770

$
(10,814
)

Weighted average shares outstanding – basic

47,782

48,232

Weighted average shares outstanding – diluted

47,853

48,232

Earnings (loss) per common share – basic

$
0.02

$
(0.22
)
Earnings (loss) per common share – diluted

$
0.02

$
(0.22
)
Dividend per share

$
0.09

$
0.09

	March 31,			December 31,
	2020			2019
ASSETS
Current Assets
Cash and cash equivalents	$	71,285		$	73,773
Short-term investments		5,984			33,243
Accounts receivable, less allowance for doubtful accounts of $38 as of March 31, 2020 and December 31, 2019		86,465			90,531
Other receivables		23,121			16,566
Inventory, net		99,515			98,305
Prepaid expenses and other current assets		7,419			7,892
Total Current Assets		293,789			320,310
Property, plant and equipment, net		66,500			68,086
Deferred tax assets, net		7,447			7,561
Goodwill		6,968			6,968
Intangibles, net		26,472			27,821
Other assets		17,958			19,883
Long-term investments		79,136			94,489
Total Assets	$	498,270		$	545,118
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities
Accounts payable	$	47,685		$	44,870
Bonds payable		—			24,600
Unearned revenue		12,465			11,963
Accrued expenses and other liabilities		12,748			13,876
Accrued wages and benefits		13,247			13,890
Income tax payable, net		3,273			3,512
Total Current Liabilities		89,418			112,711
Non-current unearned revenue		4,476			6,012
Pension liability		15,546			15,886
Deferred compensation liability		18,321			21,698
Other non-current liabilities		6,794			8,385
Total Liabilities		134,555			164,692
Commitments and contingencies (see Note 17)
Stockholders’ Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 79,652 shares issued and 47,957 shares outstanding as of March 31, 2020 and 79,652 shares issued and 48,020 shares outstanding as of December 31, 2019		797			797
Additional paid-in capital		276,423			274,632
Accumulated other comprehensive loss		(17,809	)		(16,417	)
Retained earnings		790,849			806,702
Treasury stock at cost: 31,697 and 31,638 shares at March 31, 2020 and December 31, 2019, respectively		(686,545	)		(685,288	)
Total Stockholders’ Equity		363,715			380,426
Total Liabilities and Stockholders’ Equity	$	498,270		$	545,118

	Three Months Ended
	March 31,
	2020			2019
Sales
Network Solutions	$	97,372		$	125,822
Services & Support		17,151			17,969
Total Sales		114,523			143,791
Cost of Sales
Network Solutions		51,626			70,734
Services & Support		11,297			12,445
Total Cost of Sales		62,923			83,179
Gross Profit		51,600			60,612
Selling, general and administrative expenses		26,620			35,132
Research and development expenses		29,859			31,647
Asset impairments		65			—
Operating Loss		(4,944	)		(6,167	)
Interest and dividend income		356			591
Interest expense		(1	)		(127	)
Net investment gain (loss)		(10,877	)		5,926
Other income, net		1,129			855
Income (Loss) Before Income Taxes		(14,337	)		1,078
Income tax (expense) benefit		4,368			(308	)
Net Income (Loss)	$	(9,969	)	$	770

Weighted average shares outstanding – basic		47,957			47,782
Weighted average shares outstanding – diluted		47,957			47,853

Earnings (loss) per common share – basic	$	(0.21	)	$	0.02
Earnings (loss) per common share – diluted	$	(0.21	)	$	0.02

	Three Months Ended						Three Months Ended
	March 31,						March 31,
	2019			2018			2020			2019
Net Income (Loss)	$	770		$	(10,814	)	$	(9,969	)	$	770
Other Comprehensive Loss, net of tax
Net unrealized gains (losses) on available-for-sale securities		185			(3,412	)
Net unrealized gains on available-for-sale securities								117			185
Defined benefit plan adjustments		121			62			141			121
Foreign currency translation		(1,160	)		842			(1,650	)		(1,160	)
Other Comprehensive Loss, net of tax		(854	)		(2,508	)		(1,392	)		(854	)
Comprehensive Loss, net of tax	$	(84	)	$	(13,322	)	$	(11,361	)	$	(84	)

Common
Shares

Common
Stock

Additional
Paid-In
Capital

Retained
Earnings

Treasury
Stock

Accumulated Other Comprehensive Loss

Total
Stockholders'
Equity

Balance at January 1, 2018

79,652

$
797

$
260,515

$
922,178

$
(682,284
)

$
(3,295
)

$
497,911

Net loss

(10,814
)

(10,814
)
Adoption of new accounting standards

3,499

3,499

Other comprehensive loss, net of tax

(2,508
)

(2,508
)
Dividend payments

(4,367
)

(4,367
)
Dividends accrued on unvested restricted
stock units

(2
)

(2
)
Stock options exercised

(150
)

519

369

PSUs, RSUs and restricted stock vested

(733
)

733

—

Purchase of treasury stock

(10,171
)

(10,171
)
Stock-based compensation expense

1,819

1,819

Balance at March 31, 2018

79,652

$
797

$
262,334

$
909,611

$
(691,203
)

$
(5,803
)

$
475,736

	Common Shares		Common Stock		Additional Paid-In Capital		Retained Earnings			Treasury Stock			Accumulated Other Comprehensive Loss			Total Stockholders' Equity
Balance as of January 1, 2019		79,652	$	797	$	267,670	$	883,975		$	(691,747	)	$	(14,416	)	$	446,279
Net income		—		—		—		770			—			—			770
Adoption of new accounting standards		—		—		—		(381	)		—			385			4
Other comprehensive loss, net of tax		—		—		—		—			—			(854	)		(854	)
Dividend payments ($0.09 per share)		—		—		—		(4,301	)		—			—			(4,301	)
Dividends accrued on unvested RSUs		—		—		—		(18	)		—			—			(18	)
PSUs, RSUs and restricted stock vested		—		—		—		(865	)		857			—			(8	)
Purchases of treasury stock		—		—		—		—			(184	)		—			(184	)
Stock-based compensation expense		—		—		1,859		—			—			—			1,859
Balance as of March 31, 2019		79,652	$	797	$	269,529	$	879,180		$	(691,074	)	$	(14,885	)	$	443,547

Common
Shares

Common
Stock

Additional
Paid-In
Capital

Retained
Earnings

Treasury
Stock

Accumulated Other Comprehensive Loss

Total
Stockholders'
Equity

Balance at January 1, 2019

79,652

$
797

$
267,670

$
883,975

$
(691,747
)

$
(14,416
)

$
446,279

Net income

770

770

Adoption of new accounting standards (See Note 1)

(381
)

385

4

Other comprehensive loss, net of tax

(854
)

(854
)
Dividend payments

(4,301
)

(4,301
)
Dividends accrued on unvested restricted
stock units

(18
)

(18
)
PSUs, RSUs and restricted stock vested

(865
)

857

(8
)
Purchase of treasury stock

(184
)

(184
)
Stock-based compensation expense

1,859

1,859

Balance at March 31, 2019

79,652

$
797

$
269,529

$
879,180

$
(691,074
)

$
(14,885
)

$
443,547

	Common Shares		Common Stock		Additional Paid-In Capital		Retained Earnings			Treasury Stock			Accumulated Other Comprehensive Loss			Total Stockholders' Equity
Balance as of January 1, 2020		79,652	$	797	$	274,632	$	806,702		$	(685,288	)	$	(16,417	)	$	380,426
Net loss		—		—		—		(9,969	)		—			—			(9,969	)
Other comprehensive loss, net of tax		—		—		—		—			—			(1,392	)		(1,392	)
Dividend payments ($0.09 per share)		—		—		—		(4,328	)		—			—			(4,328	)
Dividends accrued on unvested RSUs		—		—		—		(32	)		—			—			(32	)
Deferred compensation adjustments, net of tax		—		—		—		—			(2,758	)		—			(2,758	)
PSUs, RSUs and restricted stock vested		—		—		—		(1,524	)		1,501			—			(23	)
Stock-based compensation expense		—		—		1,791		—			—			—			1,791
Balance as of March 31, 2020		79,652	$	797	$	276,423	$	790,849		$	(686,545	)	$	(17,809	)	$	363,715

	Three Months Ended
	March 31,						March 31,
	2019			2018			2020			2019
Cash flows from operating activities:
Net income (loss)	$	770		$	(10,814	)	$	(9,969	)	$	770
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		4,496			3,614			4,365			4,496
Asset impairments								65			—
Amortization of net premium on available-for-sale investments		6			42			61			6
Net (gain) loss on long-term investments		(5,926	)		97			10,877			(5,926	)
Net (gain) loss on disposal of property, plant and equipment		(6	)		67			52			(6	)
Gain on bargain purchase of a business		—			(11,322	)
Stock-based compensation expense		1,859			1,819			1,791			1,859
Deferred income taxes		235			(1,877	)		(63	)		235
Changes in operating assets and liabilities:
Accounts receivable, net		170			63,904			3,052			170
Other receivables		2,001			(6,598	)		(6,707	)		2,001
Inventory, net		5,974			3,368			(1,598	)		5,974
Prepaid expenses and other assets		2,809			10,583			2,206			2,809
Accounts payable, net		166			(10,233	)		2,712			166
Accrued expenses and other liabilities		(2,355	)		826			(6,680	)		(2,355	)
Income tax payable		(487	)		2,753
Net cash provided by operating activities		9,712			46,229
Income taxes payable								(188	)		(487	)
Net cash provided by (used in) operating activities								(24	)		9,712

Cash flows from investing activities:
Purchases of property, plant and equipment		(1,872	)		(1,950	)		(1,406	)		(1,872	)
Proceeds from sales and maturities of debt and equity investments		17,039			49,074
Purchases of debt and equity investments		(15,318	)		(75,960	)
Acquisition of business		—			(7,806	)
Net cash used in investing activities		(151	)		(36,642	)
Proceeds from sales and maturities of available-for-sale investments								46,440			17,039
Purchases of available-for-sale investments								(16,879	)		(15,318	)
Acquisition of note receivable								(523	)		—
Net cash provided by (used in) investing activities								27,632			(151	)

Cash flows from financing activities:
Proceeds from stock option exercises		—			369
Purchases of treasury stock		(184	)		(10,171	)		—			(184	)
Dividend payments		(4,301	)		(4,367	)		(4,328	)		(4,301	)
Repayment of bonds payable								(24,600	)		—
Net cash used in financing activities		(4,485	)		(14,169	)		(28,928	)		(4,485	)

Net increase (decrease) in cash and cash equivalents		5,076			(4,582	)		(1,320	)		5,076
Effect of exchange rate changes		(1,461	)		772			(1,168	)		(1,461	)
Cash and cash equivalents, beginning of period		105,504			86,433			73,773			105,504
Cash and cash equivalents, end of period	$	109,119		$	82,623		$	71,285		$	109,119

Supplemental disclosure of non-cash investing activities:
Purchases of property, plant and equipment included in accounts payable	$	273		$	95		$	302		$	273

The accompanying unaudited condensed consolidated financial statements of ADTRAN^®, Inc. and its subsidiaries (“ADTRAN”, the “Company”, “we”, “our” or ~~the “Company”~~“us”) have been prepared pursuant to the rules and regulations ~~for reporting on~~of the Securities and Exchange Commission (the “SEC”) applicable to interim financial information presented in Quarterly Reports on Form 10-Q. Accordingly, certain information and notes required by generally accepted accounting principles in the United States of America (“U.S. GAAP”) for complete financial statements are not included herein. The December 31, ~~2018~~2019 Condensed Consolidated Balance Sheet is derived from audited financial statements but does not include all disclosures required by ~~accounting principles generally accepted in the United States.~~U.S. GAAP.

In the opinion of management, all adjustments necessary to fairly state these interim statements have been recorded and are of a normal and recurring nature. The results of operations for an interim period are not necessarily indicative of the results for the full year. The interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in ADTRAN’s Annual Report on Form 10-K for the year ended December 31, ~~2018,~~2019, filed with the SEC on February ~~28, 2019 with the SEC.~~25, 2020.

The preparation of financial statements in conformity with ~~accounting principles generally accepted in the United States of America~~U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. ~~Our~~The more significant estimates include ~~the~~excess and obsolete ~~and excess~~ inventory reserves, warranty reserves, customer rebates, determination and accrual of ~~the~~ deferred ~~and accrued~~ revenue components of ~~multiple~~ element sales agreements, estimated costs to complete obligations associated with deferred and accrued ~~revenue,~~revenues and network installations, estimated income tax provision and income tax contingencies, ~~the~~ fair value of stock-based compensation, ~~impairment~~assessment of goodwill ~~valuation~~ and other intangibles for impairment, estimated lives of intangible assets, estimated pension liability ~~fair value of investments~~ and ~~the evaluation of other-than-temporary declines in the~~fair value of investments. Actual amounts could differ significantly from these estimates.

~~Recent~~We assessed certain accounting matters that generally require consideration of forecasted financial information in context with the information reasonably available to us and the unknown future impacts of the novel coronavirus (“COVID-19”) as of March 31, 2020 and through the date of this report. The accounting matters assessed included, but were not limited to, the allowance for doubtful accounts, stock-based compensation, carrying value of goodwill, intangibles and other long-lived assets, financial assets, valuation allowances for tax assets and revenue recognition. While there was not a material impact to our consolidated financial statements as of and for the quarter ended March 31, 2020 resulting from these assessments, future assessments of our current expectations at that time of the magnitude and duration of the COVID-19 pandemic, as well as other factors, could result in material impacts to our consolidated financial statements in future reporting periods.

During the three months ended June 30, 2019, it was determined that a $1.0 million cash inflow related to an insurance recovery was incorrectly classified as a cash flow from operations instead of a cash flow from investing activities within the unaudited Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2019. The Company corrected this misstatement in the unaudited Condensed Consolidated Statement of Cash Flows as an out of period adjustment as of and for the six months ended June 30, 2019 to correctly reflect the $1.0 million insurance recovery as a cash inflow from investing activities. Management had previously determined that this misstatement was not material to any of its previously issued financial statements on either a quantitative or qualitative basis.

During the three months ended March 31, 2020, it was determined that certain investments held in the Company’s stock for a deferred compensation plan accounted for as a Rabbi trust were incorrectly classified as Long-term investments with the fair value of such investments incorrectly marked to market at each period end rather than classified as Treasury stock held at historical cost. This plan has been in existence since 2011. The Company corrected this misstatement as an out of period adjustment in the three months ended March 31, 2020 by remeasuring the investment assets to their historical cost basis through the recording of a Net investment gain of $1.5 million in the unaudited Condensed Consolidated Statement of Income (Loss) and then correcting the classification by decreasing the Long-term investment balance at its remeasured cost basis of $2.8 million to Treasury stock in the unaudited Condensed Consolidated Balance Sheet as of March 31, 2020. Management has determined that this misstatement was not material to any of its previously issued financial statements and that correction of the misstatement is also not expected to be material to the 2020 annual financial results on either a quantitative or qualitative basis.

During 2020, we adopted the following accounting standards, which had the following impacts on our consolidated financial statements:

In June 2016, the Financial Accounting Standards Board ~~(FASB)~~(“FASB”) issued Accounting Standards Update ~~(ASU)~~(“ASU”) 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires the measurement and recognition of expected credit losses for financial instruments held at amortized cost. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326 Financial Instruments – Credit Losses, that clarifies receivables arising from operating leases are not within the scope of the credit losses standard, but rather should be accounted for in accordance with the ~~leases standard.~~standard for leases. In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments–Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which clarifies the accounting for transfers between classifications of debt securities and clarifies that entities should include expected recoveries on financial assets in the calculation of the current expected credit loss allowance. In addition, renewal options that are not unconditionally cancelable should be considered in the determination of expected credit losses. In May 2019, the FASB issued ASU 2019-05, Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief, which amends ASU 2016-13 to allow companies, upon adoption, to elect the fair value option on financial instruments that were previously recorded at amortized cost if they meet certain criteria. In November 2019, the FASB issued ASU 2019-11, Codification improvements to Topic 326, Financial Instruments – Credit Losses, which makes various narrow-scope amendments to the new credit losses standard, such as providing disclosure relief for accrued interest receivables. All of these ASUs were codified as part of ASC Topic 326 and ~~ASU 2018-19 are~~were effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, ~~2019, with early~~2019. The Company adopted this standard on January 1, 2020, using a modified-retrospective approach and, therefore, elected to carry forward legacy disclosures for comparative periods and did not adjust the comparative period financial information. Additionally, the Company made an accounting policy election, at the class of financing receivable, not to measure the allowance for credit losses for accrued interest receivables, as the Company writes off the uncollectable accrued interest receivable by reversing any previously recorded interest income in a timely manner (as soon as these amounts are determined to be uncollectable). The adoption ~~permitted. We are currently evaluating the~~of this standard did not have a material effect ~~ASU 2016-13 and ASU 2018-19 will have~~ on our consolidated financial statements.See Note 18 for additional information.

In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. ASU 2017-04 simplifies the measurement of goodwill by eliminating step 2 of the goodwill impairment test. Under ASU 2017-04, entities ~~will be~~are required to compare the fair value of a reporting unit to its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. ASU 2017-04 iswas effective for annual or interim impairment tests performed in fiscal years beginning after December 15, ~~2019, with early adoption permitted for annual or interim impairment tests performed~~2019. The Company adopted ASU 2017-04 on ~~testing dates after~~ January 1, ~~2017. The~~2020, and the amendments ~~should be~~were applied prospectively. ~~We are currently evaluating whether to early adopt ASU 2017-04, but do~~The adoption of this standard did not ~~expect it will~~ have a material effect on our consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure ~~Framework-Changes~~Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which changes the fair value measurement disclosure requirements of ASC 820, Fair Value Measurement. The amendments in this ASU are the result of a broader disclosure project, ~~called,~~ Concepts Statement No. 8 -— Conceptual Framework for Financial Reporting — Chapter 8 — Notes to Financial Statements, which the FASB finalized on August 28, 2018. The FASB used the guidance in the Concepts Statement to improve the effectiveness of ASC 820’s disclosure requirements. ASU 2018-13 provides users of financial statements with information about assets and liabilities measured at fair value in the statement of financial position or disclosed in the notes to the financial statements. More specifically, ASU 2018-13 requires disclosures about the valuation techniques and inputs that are used to arrive at measures of fair value, including judgments and assumptions that are made in determining fair value. In addition, ASU 2018-13 requires disclosures regarding the uncertainty in the fair value measurements as of the reporting date and how changes in fair value measurements affect performance and cash flows. The Company adopted ASU 2018-13 ~~is effective for fiscal years,~~on January 1, 2020, and ~~interim periods within those fiscal years, beginning after December 15, 2019. We are currently evaluating~~ the ~~effect~~adoption of ~~ASU 2018-13, but do~~this standard did not ~~expect it will~~ have a material effect on our consolidated financial ~~statement disclosures.~~statements.

In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal – Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 clarifies certain aspects of ASU 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement. Specifically, ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementations costs incurred to develop or obtain internal use software. The Company adopted ASU 2018-15 on January 1, 2020, retrospectively. The adoption of this standard resulted in a reclassification of $5.6 million from property, plant and equipment to other assets for certain previously capitalized costs related to information technology implementation projects that had not yet been placed in service on the consolidated balance sheet as of March 31, 2020 and December 31, 2019. There was minimal impact to previously reported net cash provided by (used in) operations on the statement of cash flows and no impact to the statements of income (loss) as no portion of the capitalized asset was depreciated in prior periods.

The following table illustrates the impact of adoption of ASU 2018-15 on the Condensed Consolidated Balance Sheet as of December 31, 2019:

The following table illustrates the impact of adoption of ASU 2018-15 on the Condensed Consolidated Statement of Income and Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2019:

In August 2018, the FASB issued ASU2018-14, ~~Compensation-Retirement Benefits-Defined~~Compensation – Retirement Benefits – Defined Benefit ~~Plans-General~~Plans – General (Subtopic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans, which makes changes to and clarifies the disclosure requirements related to defined benefit pension and other postretirement plans. ASU 2018-14 requires additional disclosures related to the reasons for significant gains and losses affecting the benefit obligation and an explanation of any other significant changes in the benefit obligation or plan assets that are not otherwise apparent in other disclosures required by ASC 715. ASU 2018-14 also clarifies the guidance in ASC 715 to require disclosure of the projected benefit obligation ~~(PBO)~~(“PBO”) and fair value of plan assets for pension plans with PBOs in excess of plan assets and the accumulated benefit obligation ~~(ABO)~~(“ABO”) and fair value of plan assets for pension plans with ABOs in excess of plan assets. ASU 2018-14 is effective for public business entities for fiscal years ending after December 15, 2020. ~~We are~~The Company is currently evaluating the ~~effect of ASU 2018-14, but do not expect it~~impact this guidance will have ~~a material effect~~ on ~~our financial statement~~its related disclosures.

In ~~August 2018,~~December 2019, the FASB issued ASU ~~2018-15,~~2019-12, ~~Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40), Customer’s~~Income Taxes (Topic 740): Simplifying the Accounting for ~~Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.~~Income Taxes, ~~ASU 2018-15 clarifies certain aspects of ASU 2015-05,~~ ~~Customer’s Accounting~~which simplifies the accounting for ~~Fees Paid in a Cloud Computing Arrangement.~~ ~~Specifically, ASU 2018-15 aligns~~income taxes by removing various exceptions, such as the ~~requirements~~exception to the incremental approach for ~~capitalizing implementation costs incurred in a hosting arrangement that~~intra-period tax allocation when there is a ~~service contract with~~loss from continuing operations and income or a gain from other items. The amendments in this update also simplify the ~~requirements~~accounting for ~~capitalizing implementations costs incurred~~income taxes related to ~~develop~~income-based franchise taxes and require that an entity reflect enacted tax laws or ~~obtain internal use software.~~rates in the annual effective tax rate computation in the interim period that includes the enactment date. ASU ~~2018-15~~2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, ~~2019,~~2020, with early adoption permitted. ~~We are~~The Company is currently evaluating the ~~effect~~impact of ~~ASU 2018-15, but do not expect it will have a material effect~~this new standard on ~~our~~its consolidated financial statements.

~~During 2019, we adopted the following accounting standards, which had the following effects on our consolidated financial statements:~~

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). ASU 2016-02 requires an entity to recognize right-of-use assets and lease liabilities on the balance sheet and to disclose key information about the entity’s leasing arrangements. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases, which clarified certain aspects of ASU 2016-02, as well as, ASU 2018-11, Leases (Topic 842), Targeted Improvements, which provided for an optional transition method which allowed for the application of the legacy lease guidance, including its disclosure requirements, for the comparative periods presented in the year of adoption, with the cumulative effect of initially applying the new lease standard recognized as an adjustment to retained earnings as of the date of adoption. In March 2019, the FASB issued ASU 2019-01, Leases (Topic 824) Codification Improvements, which removed the requirement for an entity to disclose in the interim periods after adoption, the effect of the change on income from continuing operations, net income, any other affected financial statement line item, and any affected per share amount. For lessors, the new leasing standard requires leases to be classified as a sales-type, direct financing or operating leases. These criteria focus on the transfer of control of the underlying lease asset. This standard and related updates were effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years.

The Company adopted the new standard on January 1, 2019, the effective date of our initial application, using the optional transition method. The Company has elected to carry forward the legacy (ASC 840) disclosures for comparative periods and therefore, did not adjust the comparative period financial information prior to January 1, 2019. In addition, the Company elected the package of practical expedients which allows for companies to not reassess whether any expired or existing contracts are or contain leases, not reassess historical lease classifications for expired or existing contracts and not reassess initial direct costs for existing leases. Additionally, the Company elected the practical expedients which allow the use of hindsight when determining the lease term, the short-term lease recognition exemption and the option to not separate lease and non-lease components. The adoption of this standard resulted in the recognition of a right-of-use asset and corresponding right-of-use liability on our Consolidated Balance Sheet of $10.3 million, mainly related to our operating leases for office space, automobiles and other equipment.

~~As a lessee, the adoption of this standard did not have a material impact on our Consolidated Statement of Income or Statement of Cash Flow. See Note 12 for additional information.~~

As a lessor, the adoption of this standard did not have a material impact on the Company’s Consolidated Balance Sheet, Consolidated Statement of Income or Statement of Cash Flow. Prior to and after adoption, all of our leases in which we are the lessor were classified as sales-types leases.

~~In March 2017, the FASB issued ASU 2017-08,~~ ~~Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities~~, which shortened the amortization period for the premium on certain purchased callable debt securities to the earliest call date. ASU 2017-08 was effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2018. The amendments were required to be applied through a modified-retrospective transition approach that required a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company adopted ASU 2017-08 on January 1, 2019, and the adoption of this standard did not have a material effect on our consolidated financial statements.

~~In August 2017, the FASB issued ASU 2017-12,~~ ~~Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities~~. ASU 2017-12 expanded and refined hedge accounting for both financial and non-financial risk components, aligned the recognition and presentation of the effects of hedging instruments and hedge items in the financial statements, and included certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. In October 2018, the FASB issued ASU 2018-16, ~~Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting,~~ which permits the OIS rate based on SOFR as a U.S. benchmark interest rate. Both ASU 2017-12 and ASU 2018-16 were effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company adopted ASU 2017-12 on January 1, 2019, and the adoption of this standard did not have a material effect on our consolidated financial statements as we currently do not have any hedging instruments.

~~In February 2018, the FASB issued ASU 2018-02,~~ ~~Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Comprehensive Income.~~ ASU 2018-02 allowed for an optional reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. ASU 2018-02 was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company adopted ASU 2018-02 on January 1, 2019, and upon adoption reclassified $0.4 million of stranded tax effects created by rate changes related to the Tax Cuts and Jobs Act of 2017 to retained earnings. ~~See Note 13 for additional information.~~

On November 30, 2018, we acquired SmartRG, Inc., a provider of carrier-class, open-source connected home platforms and cloud services for broadband service providers in exchange for cash consideration. This transaction was accounted for as a business combination. We have included the financial results of this acquisition in our consolidated financial statements since the date of acquisition. This revenue is included in the Subscriber Solutions & Experience category within the Network Solutions and Services & Support reportable segments.

Contingent liabilities with a fair value totaling $1.2 million were recognized at the acquisition date, the payments of which are dependent upon SmartRG achieving future revenue, EBIT or customer purchase order milestones during the first half of 2019. The contingent payments are subject to arbitration and the final payouts, if applicable, are expected to occur during the third quarter of 2019. The minimum and maximum potential payment under the total of the contingent liabilities ranges from no payment to $1.5 million. As of March 31, 2019, the fair value of the contingent liability was re-assessed and was determined to be $1.2 million, based on the expected probable outcomes. No change in fair value was recognized during the three months ended March 31, 2019.

An escrow in the amount of $2.8 million was set up at the acquisition date, to fund post-closing working capital settlements and to indemnify the Company from any inaccuracy or breach of representations, warranties, covenants, agreements or obligations of the sellers. The escrow is subject to arbitration with final settlement expected during the fourth quarter of 2020. The minimum and maximum potential release of funds to the seller ranges from no payment to $2.8 million.

We recorded goodwill of $3.5 million as a result of this acquisition, which represents the excess of the purchase price over the fair value of net assets acquired. We assessed the recognition and measurement of the assets acquired and liabilities assumed based on historical and forecasted data for future periods and concluded that our valuation procedures and resulting measures were appropriate.

On March 19, 2018, we acquired Sumitomo Electric Lightwave Corp.’s (SEL) North American EPON business and entered into a technology license and OEM supply agreement with Sumitomo Electric Industries, Ltd. (SEI). This transaction was accounted for as a business combination. We have included the financial results of this acquisition in our consolidated financial statements since the date of acquisition. This revenue is included in the Access & Aggregation and Subscriber Solutions & Experience categories within the Network Solutions reportable segment.

We recorded a bargain purchase gain, net of income taxes, of $11.3 million during the first quarter of 2018, which represents the difference between the fair value of the net assets acquired over the cash paid. We assessed the recognition and measurement of the assets acquired and liabilities assumed based on historical and forecasted data for future periods and concluded that our valuation procedures and resulting measures were appropriate.

~~The final allocation of the purchase price to the estimated fair value of the assets acquired and liabilities assumed at the acquisition date for SmartRG and Sumitomo are as follows:~~

The actual revenue and net loss included in the Consolidated Statements of Income for SmartRG and Sumitomo for the three months ended March 31, 2019 and from March 19, 2018 to March 31, 2018 are as follows:

~~The details of the acquired intangible assets from these acquisitions are as follows:~~

The following unaudited supplemental pro forma information presents the financial results of the Company as if the acquisition of SmartRG and Sumitomo had occurred on January 1, 2018. This unaudited supplemental pro forma information does not purport to be indicative of what would have occurred had the acquisition been completed on January 1, 2018, nor is it indicative of any future results. Aside from revising the 2018 net income for the effect of the bargain purchase gain, there were no material, non-recurring adjustments to this unaudited pro forma information.

For the three months ended March 31, 2019 and 2018, we incurred acquisition and integration related expenses and amortization of acquired intangibles of $1.3 million and $0.2 million respectively, related to these acquisitions.

The following is a description of the principal activities from which ~~we generate our~~ revenue is generated by reportable ~~segment.~~segment:

~~Network Solutions includes~~ - Includes hardware products and software-defined next-generation virtualized solutions used in service provider or business networks, as well as prior generation products. The majority of the revenue from this segment is from hardware sales. In certain transactions, we are also the lessor in sales-type lease arrangements for network equipment. These arrangements typically include network equipment, network implementation services and maintenance services. See Note 12 for additional information.

~~To complement our Network Solutions segment, we offer a complete portfolio of~~ - Includes maintenance, network implementation, ~~and~~ solutions integration and managed services, which include hosted cloud services and subscription services.

In addition to our reporting segments, werevenue is also ~~report revenue in~~reported for the following ~~three~~3 categories – Access & Aggregation, Subscriber Solutions & Experience and Traditional & Other Products.

The following table disaggregates ~~our~~ revenue by ~~major source~~reportable segment and revenue category for the three months ended March 31, 2020 and 2019:

~~The following table disaggregates our revenue by major source for the three months ended March 31, 2018:~~

⁽¹⁾

Subscriber Solutions & Experience was formerly reported as Customer Devices. With the increasing focus on enhancing the customer experience for both our business and consumer broadband customers and the addition of SmartRG during the fourth quarter of 2018, Subscriber Solutions & Experience more accurately represents this revenue category.

	Three Months Ended
	March 31, 2020						March 31, 2019
(In thousands)	Network Solutions		Services & Support		Total		Network Solutions		Services & Support		Total
Access & Aggregation	$	53,055	$	12,911	$	65,966	$	85,673	$	14,105	$	99,778
Subscriber Solutions & Experience		39,983		2,196		42,179		34,719		2,034		36,753
Traditional & Other Products		4,334		2,044		6,378		5,430		1,830		7,260
Total	$	97,372	$	17,151	$	114,523	$	125,822	$	17,969	$	143,791

Revenue allocated to remaining performance obligations represents contract revenues that have not yet been recognized for contracts with a duration greater than one year. As of March 31, ~~2019,~~2020, we did ~~not~~0t have any significant performance obligations related to customer contracts that had an original expected duration of one year or more, other than maintenance services, which are satisfied over time.

As a practical expedient, for certain contracts we recognize revenue equal to the amounts we are entitled to invoice which correspond to the value of completed performance obligations to date. The amount related to these performance obligations was $14.3 million and $13.6 million as of March 31, 2020 and December 31, 2019, respectively. The Company expects to recognize 69% of the $14.3 million as of March 31, 2020 over the next 12 months with the remainder to be recognized thereafter.

The following table provides information about receivables, contract assets and unearned revenue from contracts with customers:

(In thousands)	March 31, 2019		December 31, 2018		March 31, 2020		December 31, 2019
Accounts receivable, net	$	99,032	$	99,385	$	86,465	$	90,531
Contract assets(1)	$	2,333	$	3,766	$	1,354	$	2,812
Unearned revenue	$	15,230	$	17,940	$	12,465	$	11,963
Non-current unearned revenue	$	4,514	$	5,296	$	4,476	$	6,012

~~$6.9 million of~~Of the outstanding unearned revenue ~~balance at~~balances as of December 31, 2019 and December 31, 2018, $5.7 million and $6.9 million was recognized as revenue during the three months ended March 31, ~~2019.~~2020 and March 31, 2019, respectively.

Our effective tax rate ~~increased~~decreased from an expense of ~~15.1%, excluding the tax effect of the bargain purchase gain, in~~28.6% for the three months ended March 31, ~~2018,~~2019, to ~~an expense~~a benefit of ~~28.6% in~~30.5% for the three months ended March 31, ~~2019.~~2020. The ~~increase~~decrease in the effective tax rate between the two periods iswas primarily driven by a tax benefit of $7.4 million recognized during the ~~shift~~three months ended March 31, 2020 as a result of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) signed into law on March 27, 2020, which allowed for the carryback of federal net operating losses, partially offset with tax expense in our international operations and changes in our valuation allowance related to ~~profitability~~our domestic operations. The increase in the ~~current quarter.~~valuation allowance against our domestic deferred tax assets was recorded in the amount of $6.1 million during the three months ended March 31, 2020.

The Company continually reviews the adequacy of ~~the~~its valuation allowance and recognizes the benefits of deferred tax assets only as the reassessment indicates that it is more likely than not that the deferred tax assets will be recognized in accordance with ASC 740, Income ~~Taxes (ASC 740).~~ Taxes. As of March 31, ~~2019, we~~2020, the Company had ~~net~~ deferred tax assets ~~of $36.9 million. Since management continues to assess~~totaling $62.2 million, and a valuation allowance totaling $54.7 million had been established against those deferred tax assets. The remaining $7.4 million in deferred tax assets not offset by a valuation allowance is located in various foreign jurisdictions where the ~~realization of~~Company believes it is more likely than not we will realize these deferred tax ~~assets and related valuation allowance(s), as such, we may release a portion~~assets. Our assessment of the ~~valuation allowance or establish a new valuation allowance based on operations in the jurisdictions in which these~~realizability of our deferred tax assets ~~arose. Our assessment~~ includes the evaluation of evidence, some of which requires significant ~~judgment,~~judgement, including historical operating results, the evaluation of our three-year cumulative income position, future taxable income projections and tax planning strategies. Should ~~management determine~~management’s conclusion change in the future and additional valuation allowance or a partial or full release of the valuation allowance is ~~needed in the future due to not being able to absorb loss carryforwards,~~necessary, it could have a material effect on our consolidated financial statements.

Supplemental balance sheet information related to deferred tax assets as of March 31, 2020 and December 31, 2019 is as follows:

~~We maintain a defined benefit pension plan covering employees in certain foreign countries.~~

The following table summarizes the components of net periodic pension cost related to a defined benefit pension plan covering employees in certain foreign countries for the three months ended March 31, ~~2019~~2020 and ~~2018:~~2019:

	Three Months Ended						Three Months Ended
	March 31,						March 31,
(In thousands)	2019			2018			2020			2019
Service cost	$	375		$	308		$	310		$	375
Interest cost		162			187			108			162
Expected return on plan assets		(355	)		(399	)		(410	)		(355	)
Amortization of actuarial losses		203			64			237			203
Net periodic pension cost	$	385		$	160		$	245		$	385

The components of net periodic pension cost, other than the service cost component, are included in other income (expense), net in the Condensed Consolidated Statements of ~~Income.~~Income (Loss). Service cost ~~are~~is included in cost of sales, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of ~~Income.~~Income (Loss).

The following table summarizes stock-based compensation expense related to stock options, performance stock units ~~(PSUs)~~(“PSUs”), restricted stock units ~~(RSUs)~~(“RSUs”) and restricted stock for the three months ended March 31, ~~2019~~2020 and ~~2018, which was recognized as follows:~~2019:

	Three Months Ended						Three Months Ended
	March 31,						March 31,
(In thousands)	2019			2018			2020			2019
Stock-based compensation expense included in cost of sales	$	104		$	95		$	115		$	104
Selling, general and administrative expense		1,063			1,035			1,075			1,063
Research and development expense		692			689			601			692
Stock-based compensation expense included in operating expenses		1,755			1,724			1,676			1,755
Total stock-based compensation expense		1,859			1,819			1,791			1,859
Tax benefit for expense associated with non-qualified options, PSUs, RSUs and restricted stock		(443	)		(384	)
Tax benefit for expense associated with stock options, PSUs, RSUs and restricted stock								(427	)		(443	)
Total stock-based compensation expense, net of tax	$	1,416		$	1,435		$	1,364		$	1,416

The following table ~~is a summary of our~~summarizes PSUs, RSUs and restricted stock ~~options~~ outstanding as of December 31, ~~2018~~2019 and March 31, ~~2019,~~2020 and the changes that occurred during the three months ended March 31, ~~2019:~~2020.

Number of
Stock Options
(in thousands)

Weighted Avg.
Exercise Price
(per share)

Weighted Avg.
Remaining
Contractual
Life
(in years)

Aggregate
Intrinsic Value
(in thousands)

Stock options outstanding, December 31, 2018

4,382

$
22.91

4.10

$
—

Stock options granted

—

$
—

Stock options exercised

—

$
—

Stock options forfeited

(8
)

$
15.33

Stock options expired

(33
)

$
23.13

Stock options outstanding, March 31, 2019

4,341

$
22.93

3.80

$
—

Stock options exercisable, March 31, 2019

4,098

$
23.37

3.63

$
—

	Number of Shares (in thousands)			Weighted Avg. Grant Date Fair Value (per share)
Unvested PSUs, RSUs and restricted stock outstanding, December 31, 2019		1,891		$	14.58
PSUs, RSUs and restricted stock granted		394		$	8.18
PSUs, RSUs and restricted stock vested		(13	)	$	12.32
PSUs, RSUs and restricted stock forfeited		(422	)	$	21.12
Unvested PSUs, RSUs and restricted stock outstanding, March 31, 2020		1,850		$	11.75

During the three months ended March 31, 2020, the Company issued 0.3 million performance-based PSUs to its executive officers and certain employees. The grant-date fair value of these performance-based awards is based on the closing price of the Company’s stock on the date of grant. These awards vest over a three-year period, subject to the grantee’s continued employment, with the ability to earn shares in a range of 0% to 142.8% of the awarded number of PSUs based on the achievement of defined performance targets. Equity-based compensation expense with respect to these awards will be adjusted over the vesting period to reflect the probability of achievement of performance targets defined in the award agreements.

The fair value of RSUs and restricted stock is equal to the closing price of our stock on the business day immediately preceding the grant date. The fair value of PSUs with market conditions is calculated using a Monte Carlo simulation valuation method.

As of March 31, 2020, total unrecognized compensation expense related to non-vested market-based PSUs, RSUs and restricted stock was approximately $15.3 million, which will be recognized over the remaining weighted-average period of 2.6 years. Unrecognized compensation expense will be adjusted for actual forfeitures.

As of March 31, 2020, 1.4 million shares were available for issuance under shareholder-approved equity plans in connection with the grant and exercise of stock options, PSUs, RSUs or restricted stock.

The following table summarizes stock options outstanding as of December 31, 2019 and March 31, 2020 and the changes that occurred during the three months ended March 31, 2020:

As of March 31, 2020, total unrecognized compensation expense related to non-vested stock options was approximately ~~$0.6 million,~~$7 thousand, which ~~is expected to~~will be recognized over ~~an average~~the remaining ~~recognition~~weighted-average period of ~~0.7~~0.6 years. Unrecognized compensation expense will be adjusted for actual forfeitures.

There were 0 stock options granted during the three months ended March 31, 2020 and 2019. All of the options ~~above~~ were previously issued at exercise prices that approximated fair market value at the date of grant. ~~At March 31, 2019, 2.4 million options were available for grant under the shareholder-approved plans.~~

The aggregate intrinsic ~~values in the table above represent~~value of stock options represents the total pre-tax intrinsic value (the difference between ADTRAN’s closing stock price on the last trading day of the quarter and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on March 31, ~~2019.~~2020. The amount of aggregate intrinsic value will change based on the fair market value of ADTRAN’s ~~stock.~~stock and was 0 as of March 31, 2020. The total pre-tax intrinsic value of options exercised during the three months ended March 31, ~~2019~~2020 was ~~zero.~~ 0.

The fair value of our stock options is estimated using the Black-Scholes model. The determination of the fair value of stock options on the date of grant using the Black-Scholes model is affected by our stock price, as well as assumptions regarding a number of complex and subjective variables that may have a significant impact on the fair value estimate. The stock option pricing model requires the use of several assumptions that impact the fair value estimate. These variables include, but are not limited to, the volatility of our stock price and employee exercise behaviors.

~~There were no stock options granted during the three months ended March 31, 2019 or 2018.~~

~~The following table is a summary of our PSUs, RSUs and restricted stock outstanding as of December 31, 2018 and the changes that occurred during the three months ended March 31, 2019:~~

The fair value of our PSUs with market conditions is calculated using a Monte Carlo simulation valuation method. The fair value of RSUs and restricted stock is equal to the closing price of our stock on the business day immediately preceding the grant date.

At March 31, 2019, total unrecognized compensation expense related to the non-vested portion of market-based PSUs, RSUs and restricted stock was approximately $16.1 million, which is expected to be recognized over an average remaining recognition period of 2.8 years. In addition, there was $9.0 million of unrecognized compensation expense related to the unvested 2017 performance-based PSUs, which will be recognized over the remaining requisite service period of 0.8 years if achievement of the performance obligation becomes probable. For the three months ending March 31, 2019 and 2018, no compensation expense was recognized related to these performance-based PSUs.

AtAs of March 31, ~~2019, we held~~2020, the following debt securities and other investments were included on the Condensed Consolidated Balance Sheet and recorded at ~~either~~ fair ~~value or cost:~~value:

	Amortized		Gross Unrealized					Carrying		Amortized		Gross Unrealized					Fair
(In thousands)	Cost		Gains		Losses			Value		Cost		Gains		Losses			Value
Corporate bonds	$	15,964	$	69	$	(24	)	$	16,009	$	8,967	$	43	$	(87	)	$	8,923
Municipal fixed-rate bonds		951		—		(13	)		938		931		3		—			934
Asset-backed bonds		7,171		13		(9	)		7,175		6,052		17		(76	)		5,993
Mortgage/Agency-backed bonds		4,561		6		(26	)		4,541		8,389		140		(62	)		8,467
U.S. government bonds		4,238		—		(11	)		4,227		12,788		319		(6	)		13,101
Foreign government bonds		2,159		—		(2	)		2,157
Other											442		—		—			442
Available-for-sale debt securities held at fair value	$	35,044	$	88	$	(85	)	$	35,047	$	37,569	$	522	$	(231	)	$	37,860
Restricted investment held at cost									25,600
Other investments held at cost									1,180
Total carrying value of available-for-sale investments								$	61,827

AtAs of December 31, ~~2018, we held~~2019, the following debt securities and other investments were included on the Condensed Consolidated Balance sheet and recorded at ~~either~~ fair ~~value or cost:~~value:

	Amortized		Gross Unrealized					Carrying		Amortized		Gross Unrealized					Fair
(In thousands)	Cost		Gains		Losses			Value		Cost		Gains		Losses			Value
Corporate bonds	$	20,777	$	19	$	(112	)	$	20,684	$	9,304	$	80	$	—		$	9,384
Municipal fixed-rate bonds		1,339		—		(26	)		1,313		930		—		—			930
Asset-backed bonds		5,230		5		(14	)		5,221		6,867		26		(3	)		6,890
Mortgage/Agency-backed bonds		3,833		2		(44	)		3,791		6,944		26		(8	)		6,962
U.S. government bonds		9,271		1		(66	)		9,206		12,311		21		(9	)		12,323
Foreign government bonds		592		—		(8	)		584		372		—		(1	)		371
Variable rate demand notes											800		—		—			800
Available-for-sale debt securities held at fair value	$	41,042	$	27	$	(270	)	$	40,799	$	37,528	$	153	$	(21	)	$	37,660
Restricted investment held at cost									25,600
Other investments held at cost									397
Total carrying value of available-for-sale investments								$	66,796

As of March 31, ~~2019, our~~2020, contractual maturities related to debt securities ~~had the following contractual maturities:~~and other investments were as follows:

(In thousands)	Corporate bonds		Municipal fixed-rate bonds		Asset- backed bonds		Mortgage / Agency- backed bonds		U.S. government bonds		Foreign government bonds		Corporate bonds		Municipal fixed-rate bonds		Asset- backed bonds		Mortgage / Agency- backed bonds		U.S. government bonds		Other
Less than one year	$	3,127	$	—	$	872	$	—	$	1,691	$	—	$	3,274	$	—	$	101	$	—	$	61	$	442
One to two years		8,389		—		387		289		—		1,196		3,702		934		389		584		5,376		—
Two to three years		4,493		938		976		—		1,324		961		1,947		—		1,559		1,769		7,285		—
Three to five years		—		—		3,105		827		1,212		—		—		—		2,174		107		379		—
Five to ten years		—		—		1,038		303		—		—		—		—		1,505		1,655		—		—
More than ten years		—		—		797		3,122		—		—		—		—		265		4,352		—		—
Total	$	16,009	$	938	$	7,175	$	4,541	$	4,227	$	2,157	$	8,923	$	934	$	5,993	$	8,467	$	13,101	$	442

Actual maturities may differ from contractual maturities ~~because~~as some borrowers have the right to call or prepay obligations with or without call or prepayment penalties.

Realized gains and losses on sales of debt securities are computed under the specific identification method. The following table presents gross realized gains and losses related to our debt securities:

	Three Months Ended						Three Months Ended
	March 31,						March 31,
(In thousands)	2019			2018			2020			2019
Gross realized gains on debt securities	$	41		$	—		$	43		$	41
Gross realized losses on debt securities		(19	)		(73	)		(20	)		(19	)
Total gain (loss) recognized, net	$	22		$	(73	)
Total gain recognized, net							$	23		$	22

~~Our~~The Company’s investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5% of the market value of our total investment portfolio.

At March 31, 2019, we held a $25.6 million restricted certificate of deposit that is carried at cost. This investment serves as a collateral deposit against the principal amount outstanding under loans made to ADTRAN pursuant to an Alabama State Industrial Development Authority revenue bond (the Bond), which totaled $25.6 million at March 31, 2019 and December 31, 2018. At March 31, 2019 and December 31, 2018, the estimated fair value of the Bond using a level 2 valuation technique was approximately $25.5 million and $25.4 million, respectively, based on a The Company did 0t purchase any available-for-sale debt security with ~~a comparable interest rate and maturity and a Standard and Poor’s~~ credit ~~rating of AAA. We have~~deterioration during the right to set-off the balance of the Bond with the collateral deposit in order to reduce the balance of the indebtedness. The Bond matures on January 1, 2020, and bears interest at the rate of 2% per annum. In conjunction with this program, we are eligible to receive certain economic incentives from the state of Alabama that reduce the amount of payroll withholdings we are required to remit to the state for those employment positions that qualify under this program. We are required to make payments in the amounts necessary to pay the interest on the amounts currently outstanding. It is our intent to make annual principal payments in addition to the interest amounts that are due. The restricted funds held as collateral against the principal amount of the Bond will be used to pay the outstanding principal and interest upon the Bond’s maturity on January 1,three months ended March 31, 2020.

Our marketable equity securities consist of publicly traded stock, funds and certain other investments measured at fair value or cost (where appropriate).

~~On January 1, 2018, we adopted ASU 2016-01,~~During the three months ended March 31, 2019, an outstanding note receivable of $4.3 million was repaid and reissued in the form of debt and equity. Of the outstanding $4.3 million, $3.4 million was issued as an equity investment, which ~~requires us~~represented a non-cash investing activity. We elected to ~~measure all~~record this equity ~~investments~~investment that dodoes not ~~result in consolidation and are not accounted for under the equity method at~~have a readily determinable fair value with any changes in fair value recognized in net investment gain (loss). Upon adoption, we reclassified $3.2 million of net unrealized gains related to marketable equity securities from accumulated other comprehensive income (loss) to retained earnings.

~~ASU 2016-01 also provides a~~using the measurement alternative. Under the measurement alternative, ~~for~~ equity investments that do not have a readily determinable fair value ~~in which investments~~ can be recorded at cost less impairment, if any, adjusted for observable price changes for an identical or similar investment. ~~We elected to record our equity investment that does not have a readily determinable fair value using the measurement alternative method.~~ The carrying value of this investment under the measurement alternative was $3.4 million ~~and $0~~as of December 31, 2019. During the three months ended March 31, 2020, an impairment charge of $1.6 million was recorded related to this equity investment, which is included in net investment gain (loss) on the Condensed Consolidated Statement of Income (Loss). As a result, the carrying value of this investment was $1.8 million as of March 31, ~~2019~~2020. The remaining amount, $0.9 million of the original $4.3 million note receivable, was reissued as a new note receivable, which is included in long-term investments on the Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, ~~2018, respectively.~~2019, and represented a non-cash operating activity during the three months ended March 31, 2019. NaN impairment charge was recognized related to the note receivable as it is a secured loan.

Realized and unrealized gains and losses ~~for our~~related to marketable equity securities for the three months ended March 31, ~~2019~~2020 and ~~2018~~2019 were as follows:

	Three Months Ended						Three Months Ended
	March 31,						March 31,
(In thousands)	2019			2018			2020			2019
Realized gains (losses) on equity securities sold	$	(14	)	$	398
Realized losses on equity securities sold							$	(2,436	)	$	(14	)
Unrealized gains (losses) on equity securities held		5,918			(422	)		(8,464	)		5,918
Total gain (loss) recognized, net	$	5,904		$	(24	)	$	(10,900	)	$	5,904

~~As of March 31, 2019~~U.S. GAAP establishes a three-level valuation hierarchy based upon observable and ~~2018, gross unrealized losses related to individual investments in a continuous loss position~~unobservable inputs for ~~twelve months or longer were not significant.~~

~~We have categorized our cash equivalents and our investments held at~~ fair value ~~into a three-level fair value hierarchy based on the priority~~measurement of ~~the inputs to the valuation technique for the cash equivalents and investments as follows:~~financial instruments:

• Level 1 ~~- Values~~– Observable outputs; values based on unadjusted quoted prices for identical assets or liabilities in an active market;

• Level 2 ~~- Values~~– Significant inputs that are observable; values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly;

• Level 3 ~~- Values~~– Significant unobservable inputs; values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs could include information supplied by investees.

The Company’s cash equivalents and investments held at fair value are categorized into this hierarchy as follows:

			Fair Value Measurements at March 31, 2019 Using								Fair Value Measurements as of March 31, 2020 Using
(In thousands)	Cost or Fair Value		Quoted Prices in Active Market for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value		Quoted Prices in Active Market for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	1,279	$	1,279	$	—	$	—	$	4,826	$	4,826	$	—	$	—
Commercial paper		6,547		—		6,547		—		500		—		500		—
Cash equivalents		7,826		1,279		6,547		—
Available-for-sale debt securities
Corporate bonds		16,009		—		16,009		—		8,923		—		8,923		—
Municipal fixed-rate bonds		938		—		938		—		934		—		934		—
Asset-backed bonds		7,175		—		7,175		—		5,993		—		5,993		—
Mortgage/Agency-backed bonds		4,541		—		4,541		—		8,467		—		8,467		—
U.S. government bonds		4,227		4,227		—		—		13,101		13,101		—		—
Foreign government bonds		2,157		—		2,157		—
Other										442		—		—		442
Marketable equity securities								—
Marketable equity securities – various industries		30,725		30,725		—		—		24,823		24,823		—		—
Equity in escrow		174		174		—		—
Deferred compensation plan assets		20,416		20,416		—		—		17,349		17,349		—		—
Total debt and equity securities at fair value		86,362		55,542		30,820		—
Other investments held at cost
Other investments		3,375		—		—		—		2,106		2,106		—		—
Total other investments held at cost		3,375		—		—		—
Total	$	97,563	$	56,821	$	37,367	$	—	$	87,464	$	62,205	$	24,817	$	442

			Fair Value Measurements at December 31, 2018 Using								Fair Value Measurements as of December 31, 2019 Using
(In thousands)	Cost or Fair Value		Quoted Prices in Active Market for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value		Quoted Prices in Active Market for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	1,554	$	1,554	$	—	$	—	$	1,309	$	1,309	$	—	$	—
Cash equivalents		1,554		1,554		—		—
Available-for-sale debt securities
Corporate bonds		20,684		—		20,684		—		9,384		—		9,384		—
Municipal fixed-rate bonds		1,313		—		1,313		—		930		—		930		—
Asset-backed bonds		5,221		—		5,221		—		6,890		—		6,890		—
Mortgage/Agency-backed bonds		3,791		—		3,791		—		6,962		—		6,962		—
U.S. government bonds		9,206		9,206		—		—		12,323		12,323		—		—
Foreign government bonds		584		—		584		—		371		—		371		—
Variable rate demand notes										800		—		800		—
Marketable equity securities
Marketable equity securities – various industries		26,763		26,763		—		—		35,501		35,501		—		—
Equity in escrow		253		253		—		—		298		298		—		—
Deferred compensation plan assets		18,256		18,256		—		—		21,698		21,698		—		—
Total debt and equity securities at fair value		86,071		54,478		31,593		—
Other investments										2,442		2,442		—		—
Total	$	87,625	$	56,032	$	31,593	$	—	$	98,908	$	73,571	$	25,337	$	—

The fair value of our Level 2 securities is calculated using a weighted average market price for each security. Market prices are obtained from a variety of industry standard data providers, ~~security master files from~~ large financial institutions and other third-party sources. These multiple market prices are used as inputs into a distribution-curve-based algorithm to determine the daily market value of each security.

~~We participate in foreign exchange forward contracts in connection with the management of exposure to fluctuations in foreign exchange rates.~~

Our cash flow hedging activities utilize foreign exchange forward contracts to reduce the risk that movements in exchange rates will adversely affect the net cash flows resulting from the planned purchase of products from foreign suppliers. Purchases of U.S. denominated inventory by our European subsidiary represent our primary exposure. Changes in theThe fair value of ~~derivatives designated as cash flow hedges are not recognized~~Level 3 securities is calculated based on unobservable inputs. Quantitative information with respect to unobservable inputs consists of third-party valuations performed in ~~current operating results, but are recorded~~accordance with ASC 820 – Fair Value Measurement. Inputs used in ~~accumulated other comprehensive income. Amounts related to cash flow hedges are reclassified from accumulated other comprehensive income when~~preparing the ~~underlying hedged item impacts earnings. This reclassification is recorded in cost of sales,~~third-party valuation included the ~~same line item of the Consolidated Statements of Income at which the effects of the hedged item are recorded.~~following assumptions, among others: estimated discount rates and fair market yields.

We have certain customers and suppliers who are invoiced or pay in a non-functional currency. Changes in the monetary exchange rates may adversely affect our results of operations and financial condition, as outstanding non-functional balances are revalued to the functional currency through profit and loss. When appropriate, we utilize foreign exchange forward contracts to help manage the volatility relating to these valuation exposures. All changes in the fair value of our derivative instruments that do not qualify for, or are not designated for hedged accounting transactions, are recognized as other income (expense), net in the Consolidated Statements of Income.

We do not hold or issue derivative instruments for trading or other speculative purposes. Our derivative instruments are recorded in the Consolidated Balance Sheets at their fair values. Our derivative instruments are not subject to master netting arrangements and are not offset in the Consolidated Balance Sheets.7. INVENTORY

~~The changes in the fair values of our derivative instruments recorded in the Consolidated Statements of Income during the three months ended March 31, 2019 and 2018 were as follows:~~

~~At March 31, 2019~~2020 and December 31, ~~2018,~~2019, inventory consisted of the following:

	March 31,		December 31,		March 31,		December 31,
(In thousands)	2019		2018		2020		2019
Raw materials	$	40,841	$	45,333	$	35,922	$	36,987
Work in process		1,513		1,638		778		1,085
Finished goods		51,255		52,877		62,815		60,233
Total	$	93,609	$	99,848
Total inventory, net					$	99,515	$	98,305

~~We establish~~Inventory reserves are established for estimated excess and obsolete ~~or unmarketable~~ inventory equal to the difference between the cost of the inventory and the estimated ~~fair~~net realizable value of the inventory based ~~upon assumptions about future demand~~on estimated reserve percentages, which consider historical usage, known trends, inventory age and market conditions. As of March 31, 2020 and December 31, 2019, inventory reserves were $35.0 million and $34.1 million, respectively.

At March 31, ~~2019~~2020 and December 31, ~~2018, raw materials reserves totaled $17.1~~2019, property, plant and equipment consisted of the following:

Long-lived assets used in operations are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the undiscounted cash flows estimated to be generated by the asset are less than the asset’s carrying value. Due to the current economic environment, particularly related to COVID-19, the Company assessed impairment triggers related to long-lived assets during the first quarter of 2020. Based on this assessment, no triggers occurred to perform an impairment test, and 0 impairment losses of long-lived assets were recorded.

Depreciation expense was $3.0 million and ~~$17.6~~$3.2 million for the three months ended March 31, 2020 and 2019, respectively, which is recorded in cost of sales, selling, general and ~~finished goods inventory reserves totaled $12.8 million~~administrative expenses and ~~$12.4 million, respectively.~~research and development expenses in the Condensed Consolidated Statements of Income (Loss).

Goodwill ~~all of which relates to our acquisitions of Bluesocket, Inc. and SmartRG,~~ was $7.0 million ~~and $7.1 million at March 31, 2019 and December 31, 2018, of which $6.6 million and $0.4 million is allocated to our Network Solutions and Services & Support reportable segments, respectively,~~ as of March 31, 2020 and December 31, 2019, ~~and~~ of which ~~$6.7~~$6.6 million and $0.4 million was allocated to our Network Solutions and Services & Support reportable segments, respectively, as of December 31, 2018. Goodwill related to our SmartRG acquisition was adjusted during the three months ended March 31, 2019, as a result of filing the SmartRG income tax returns during the quarter.respectively.

~~We evaluate~~The Company evaluates the carrying value of goodwill during the fourth quarter of each year and between annual evaluations if events occur or circumstances change that ~~would~~could more likely than not reduce the fair value of the reporting unit below its carrying amount. We ~~have elected to first~~ assess ~~the~~ qualitative factors to determine whether ~~it is more likely than not that~~ the fair value of the reporting unit to which the goodwill is assigned is less than its carrying amount ~~as a basis~~and recognize an impairment charge for ~~determining whether it is necessary to perform~~ the ~~two-step impairment test. If we determine that it is more likely than not that its~~amount by which the carrying value exceeds the fair value ~~is less than its carrying amount, then~~of the ~~two-step~~reporting unit. Due to the current economic environment, particularly related to COVID-19, the Company performed a triggering event assessment, in which no triggers were identified. Therefore, no interim impairment test ~~will be performed. Based on the results~~ of ~~our qualitative assessment in 2018, we concluded that it~~goodwill was ~~not necessary to perform the two-step~~performed as of March 31, 2020 and 0 impairment ~~test.~~of goodwill was recorded.

Intangible assets include intangibles acquired in conjunction with several acquisitions since 2011, with the most recent being SmartRG, Inc. in November 2018 and SEI’s North American EPON business and technology license and OEM supply agreement with SEI in March 2018.

~~The following table presents our intangible assets~~ as of March 31, ~~2019~~2020 and December 31, ~~2018:~~2019 consisted of the following:

	March 31, 2019							December 31, 2018							March 31, 2020							December 31, 2019
(In thousands)	Gross Value		Accumulated Amortization			Net Value		Gross Value		Accumulated Amortization			Net Value		Gross Carrying Amount		Accumulated Amortization			Net Book Value		Gross Carrying Amount		Accumulated Amortization			Net Book Value
Customer relationships	$	22,363	$	(5,797	)	$	16,566	$	22,455	$	(5,380	)	$	17,075	$	20,665	$	(6,099	)	$	14,566	$	22,356	$	(7,233	)	$	15,123
Developed technology		10,170		(2,526	)		7,644		12,801		(4,867	)		7,934		8,200		(1,693	)		6,507		10,170		(3,379	)		6,791
Licensed technology		5,900		(683	)		5,217		5,900		(520	)		5,380		5,900		(1,338	)		4,562		5,900		(1,174	)		4,726
Supplier relationships		2,800		(1,458	)		1,342		2,800		(1,108	)		1,692		2,800		(2,800	)		—		2,800		(2,508	)		292
Licensing agreements		560		(24	)		536		560		(5	)		555		560		(97	)		463		560		(79	)		481
Patents		500		(174	)		326		500		(157	)		343		500		(243	)		257		500		(226	)		274
Trade names		310		(124	)		186		310		(106	)		204		210		(93	)		117		310		(176	)		134
Total	$	42,603	$	(10,786	)	$	31,817	$	45,326	$	(12,143	)	$	33,183	$	38,835	$	(12,363	)	$	26,472	$	42,596	$	(14,775	)	$	27,821

The Company evaluates the carrying value of intangible assets whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the undiscounted cash flows estimated to be generated by the asset are less than the asset’s carrying value. Due to the current economic environment, particularly related to COVID-19, the Company assessed impairment triggers related to intangible assets during the first quarter of 2020. Based on this assessment, no triggers occurred to perform an impairment test, and 0 impairment losses of intangible assets were recorded.

Amortization expense was $1.3 ~~million and $0.4~~ million for the three months ended March 31, 2020 and 2019 and ~~2018 respectively.~~was included in cost of sales, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Income (Loss).

As of March 31, ~~2019, the~~2020, estimated future amortization expense of ~~our~~ intangible assets iswas as follows:

(In thousands)	Amount
Remainder of 2019	$	3,994
2020		4,444	$	3,111
2021		4,096		4,091
2022		3,472		3,467
2023		3,320		3,316
2024				3,223
Thereafter		12,491		9,264
Total	$	31,817	$	26,472

~~We have operating~~ leases ~~for~~consist of office space, automobiles and various other equipment in the ~~United States~~U.S. and in ~~various~~certain international locations in which we do business. ~~We also have other~~Other contracts, such as manufacturing agreements and service agreements, ~~which we review~~are reviewed to determine if they contain anany embedded lease. We specifically review these other contracts to determine whether we have the right to substantially all of the economic benefit from the use of any specified assets or the right to direct the use of any specified assets, either of which would indicate the existence of a lease.

leases. As of March 31, ~~2019, our~~2020, the operating leases ~~have~~had remaining lease terms of one month to ~~six~~five years, some of which include options to extend the leases for up to 3nine years, and some of which include options to terminate the leases within ~~3 months. For those leases that are reasonably assured to be renewed, we have included~~three months. As of March 31, 2020 and December 31, 2019, the ~~option to extend~~Company’s operating lease assets and operating lease liabilities were as part of our right of use asset and right of use liability included on the Consolidated Balance Sheet. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term. follows:

Lease expense related to ~~these~~ short-term leases (initial term of less than 12 months) was $9 thousand and $0.2 million for the three months ended March 31, 2020 and 2019, respectively, and iswas included in cost of sales, selling, general and administrative expenses onand research and development expenses in the Condensed Consolidated ~~Statement~~Statements of Income. For lease agreements entered into or reassessed after the adoption of Topic 842, we elected the practical expedient which allows us to not separate lease and non-lease components. None of our lease agreements contain any material residual value guarantees or material restrictive covenants.

~~Supplemental balance sheet information~~Income (Loss). Lease expense related to ~~operating leases is~~variable lease payments that do not depend on an index or rate, such as ~~follows:~~

~~The components of lease expense included in the Consolidated Statement of Income~~real estate taxes and insurance reimbursements, was $0.2 million and $0.1 million for the three months ended March 31, 2020 and 2019, ~~are~~respectively.

Components of lease expense included in the Condensed Consolidated Statements of Income (Loss) for the three months ended March 31, 2020 and 2019 were as follows:

As of March 31, 2020 and December 31, 2019, ~~the maturity of~~operating lease liabilities included on the Condensed Consolidated Balance ~~Sheet are~~Sheets by future maturity were as follows:

(In thousands)	Amount			March 31, 2020			December 31, 2019
Remainder of 2019	$	2,363
2020		2,185		$	2,066		$	2,856
2021		2,032			2,326			2,412
2022		1,544			1,630			1,705
2023		1,163			1,076			1,160
2024					468			482
Thereafter		747			259			264
Total lease payments		10,034			7,825			8,879
Less: Interest		(515	)		(307	)		(385	)
Present value of lease liabilities	$	9,519		$	7,518		$	8,494

Future operating lease payments include ~~$1.2~~$0.6 million related to options to extend lease terms that are reasonably certain of being ~~exercised and there~~exercised. There are no legally binding leases that have not yet ~~commenced.~~

As of December 31, 2018, future minimum rental payments under non-cancelable operating leases, including renewals determined to be reasonably assured as of December 31, 2018, with original maturities of greater than 12 months are as follows:commenced

~~Our leases do not provide an implicit borrowing rate and therefore we use an~~An incremental borrowing rate is used based on ~~the~~ information available at the commencement date in determining the present value of lease payments. ~~We used the incremental borrowing rate on January 1, 2019, for operating leases that commenced on or prior to that date.~~ The incremental borrowing rate was determined on a portfolio basis by grouping leases with similar terms as well as grouping leases based on a U.S. dollar or Euro functional currency. The actual rate is then determined based on a credit spread over LIBOR as well as the Bloomberg Curve Matrix for the U.S. Communications section. The following table provides information about the weighted average lease terms and weighted average discount rates as of March 31, 2020:

Supplemental cash flow information related to operating leases ~~were~~is as follows:

We are the lessor in sales-type lease arrangements for network equipment, which have initial terms of up to five ~~years. Our sales-type lease arrangements contain either a provision whereby the network equipment reverts back to us upon the expiration~~years, and consisted of the lease or a provision that allows the lessee to purchase the network equipment at a bargain purchase amount. In addition, our sales-type lease arrangements do not contain any residual value guarantees or material restrictive covenants. The allocation of the consideration between lease and non-lease components is determined by standalone sales price by component. The net investment in sales-type leases consists of lease receivables less unearned income. Collectability of sales-type leases is evaluated periodically at an individual customer level. At March 31, 2019 and December 31, 2018, we had no allowance for credit losses for our net investment in sales-type leases. As of March 31, 2019 and December 31, 2018, the components of the net investment in sales-type leases were as follows:

The components of sales-type lease gross profit recognized at the lease commencement date and interest income, included in the Consolidated Statement of Income for the three months ended March 31, 2019 are as follows:

~~Future minimum lease payments to be received from sales-type leases~~following as of March 31, 2020 and December 31, 2019 ~~are as follows:~~

Components of gross profit related to sales-type leases recognized at the lease commencement date and interest and dividend income included in the Condensed Consolidated Statements of Income (Loss) for the three months ended March 31, 2020 and 2019 were as follows:

12. ALABAMA STATE INDUSTRIAL DEVELOPMENT AUTHORITY FINANCING AND ECONOMIC INCENTIVES

In conjunction with the 1995 expansion of our Huntsville, Alabama facility, we were approved for participation in an incentive program offered by the State of Alabama Industrial Development Authority (the “Authority”). Pursuant to the program, in January 1995, the Authority issued $20.0 million of its taxable revenue bonds (the “Taxable Revenue Bonds”) and loaned the proceeds from the sale of the Taxable Revenue Bonds to the Company. Further advances on the Taxable Revenue Bonds were made by the Authority, bringing the total amount to $50.0 million. The Taxable Revenue Bonds’ bore interest, payable monthly with an interest rate of 2% per annum. The Taxable Revenue Bonds’ aggregate principal amount outstanding as of December 31, 2019 of $24.6 million matured on January 1, 2020 and was repaid in full on January 2, 2020, using the funds held in a certificate of deposit by the Company. This certificate of deposit, which totaled $25.6 million, was included in short-term investments on the Condensed Consolidated Balance Sheet as of December 31, 2019.

Since 1997, ~~our~~the Company’s Board of Directors has approved multiple share repurchase programs that have authorized ~~open market repurchase transactions~~repurchases of ~~our~~its common stock, which are implemented through open market or private purchases from time to time as conditions warrant. During the three months ended March 31, ~~2019,~~2020, we ~~repurchased 13,000~~did 0t repurchase shares of our common ~~stock at an average price of $14.06 per share.~~stock. As of March 31, ~~2019,~~2020, we ~~have~~had the authority to purchase an additional 2.5 million shares of our common stock under the current authorization of up to 5.0 million shares.

Other comprehensive income consists of unrealized gains (losses) on available-for-sale debt securities; reclassification adjustments for amounts included in net income related to impairments of available-for-sale debt securities, realized gains (losses) on available-for-sale debt securities, realized gains (losses) on cash flow hedges, amortization of actuarial gains (losses) related to our defined benefit plan, defined benefit plan adjustments, and foreign currency translation adjustments.Loss

The following tables present the changes in accumulated other comprehensive ~~income (loss),~~loss, net of tax, by component for the three months ended March 31, ~~2019~~2020 and ~~2018:~~2019:

Three Months Ended March 31, 2019

(In thousands)

Unrealized
Gains
(Losses)
on
Available-
for-Sale
Securities

Defined
Benefit Plan
Adjustments

Foreign
Currency
Adjustments

ASU 2018-02 Adoption

Total

Beginning balance

$
(563
)

$
(8,041
)

$
(5,812
)

$
—

$
(14,416
)
Other comprehensive income (loss) before
reclassifications

231

—

(1,160
)

—

(929
)
Amounts reclassified from accumulated other
comprehensive income (loss)

(46
)

121

—

—

75

Amounts reclassified to retained earnings ⁽¹⁾

—

—

—

385

385

Net current period other comprehensive income (loss)

185

121

(1,160
)

385

(469
)
Ending balance

$
(378
)

$
(7,920
)

$
(6,972
)

$
385

$
(14,885
)

	Three Months Ended March 31, 2020
(In thousands)	Unrealized Gains (Losses) on Available- for-Sale Securities			Defined Benefit Plan Adjustments			Foreign Currency Adjustments			ASU 2018-02 Adoption ⁽¹⁾		Total
As of December 31, 2019	$	(284	)	$	(9,226	)	$	(7,292	)	$	385	$	(16,417	)
Other comprehensive loss before reclassifications		(931	)		—			(1,650	)		—		(2,581	)
Amounts reclassified from accumulated other comprehensive income (loss)		1,048			141			—			—		1,189
Net current period other comprehensive income (loss)		117			141			(1,650	)		—		(1,392	)
As of March 31, 2020	$	(167	)	$	(9,085	)	$	(8,942	)	$	385	$	(17,809	)

	Three Months Ended March 31, 2019
(In thousands)	Unrealized Gains (Losses) on Available- for-Sale Securities			Defined Benefit Plan Adjustments			Foreign Currency Adjustments			ASU 2018-02 Adoption (1)		Total
As of December 31, 2018	$	(563	)	$	(8,041	)	$	(5,812	)	$	—	$	(14,416	)
Other comprehensive income (loss) before reclassifications		231			—			(1,160	)		—		(929	)
Amounts reclassified from accumulated other comprehensive income (loss)		(46	)		121			—			—		75
Amounts reclassified to retained earnings ⁽¹⁾		—			—			—			385		385
Net current period other comprehensive income (loss)		185			121			(1,160	)		385		(469	)
As of March 31, 2019	$	(378	)	$	(7,920	)	$	(6,972	)	$	385	$	(14,885	)

Three Months Ended March 31, 2018

(In thousands)

Unrealized
Gains
(Losses)
on
Available-
for-Sale
Securities

Defined
Benefit Plan
Adjustments

Foreign
Currency
Adjustments

Total

Beginning balance

$
2,567

$
(4,286
)

$
(1,576
)

$
(3,295
)
Other comprehensive income (loss) before
reclassifications

(257
)

—

842

585

Amounts reclassified from accumulated other
comprehensive income (loss)

65

62

—

127

Amounts reclassified to retained earnings ⁽¹⁾

(3,220
)

—

—

(3,220
)
Net current period other comprehensive income (loss)

(3,412
)

62

842

(2,508
)
Ending balance

$
(845
)

$
(4,224
)

$
(734
)

$
(5,803
)

The following tables present the details of reclassifications out of accumulated other comprehensive ~~income (loss)~~loss for the three months ended March 31, ~~2019~~2020 and ~~2018:~~2019:

	Three Months Ended March 31, 2019				Three Months Ended March 31, 2020
Details about Accumulated Other Comprehensive Income (Loss) Components	Amount Reclassified from Accumulated Other Comprehensive Income (Loss)			Affected Line Item in the Statement Where Net Income Is Presented
Unrealized gains on available-for-sale securities:
Net realized gain on sales of securities	$	62		Net investment gain (loss)
(In thousands)					Amount Reclassified from Accumulated Other Comprehensive Income (Loss)			Affected Line Item in the Statement Where Net Income Is Presented
Unrealized gains (losses) on available-for-sale securities:
Net realized losses on sales of securities					$	(1,416	)	Net investment gain (loss)
Defined benefit plan adjustments – actuarial losses		(175	)	⁽¹⁾		(204	)	⁽¹⁾
Total reclassifications for the period, before tax		(113	)			(1,620	)
Tax benefit		38				431
Total reclassifications for the period, net of tax	$	(75	)		$	(1,189	)

The following table presents the tax effects related to the change in each component of other comprehensive ~~income (loss)~~loss for the three months ended March 31, ~~2019~~2020 and ~~2018:~~2019:

Three Months Ended

Three Months Ended

March 31, 2019

March 31, 2018

(In thousands)

Before-Tax
Amount

Tax
(Expense)
Benefit

Net-of-Tax
Amount

Before-Tax
Amount

Tax
(Expense)
Benefit

Net-of-Tax
Amount

Unrealized gains (losses) on available-for-sale
   securities

$
312

$
(81
)

$
231

$
(347
)

$
90

$
(257
)
Reclassification adjustment for amounts related to
   available-for-sale investments included in net
   income

(62
)

16

(46
)

73

(8
)

65

Reclassification adjustment for amounts related to
   cash flow hedges included in net income

—

—

—

(3,220
)

—

(3,220
)
Reclassification adjustment for amounts related to
   defined benefit plan adjustments included in net
   income

175

(54
)

121

90

(28
)

62

Foreign currency translation adjustment

(1,160
)

—

(1,160
)

842

—

842

Total Other Comprehensive Income (Loss)

$
(735
)

$
(119
)

$
(854
)

$
(2,562
)

$
54

$
(2,508
)

	Three Months Ended									Three Months Ended
	March 31, 2020									March 31, 2019
(In thousands)	Before-Tax Amount			Tax (Expense) Benefit			Net-of-Tax Amount			Before-Tax Amount			Tax (Expense) Benefit			Net-of-Tax Amount
Unrealized gain (loss) on available-for-sale securities	$	(1,258	)	$	327		$	(931	)	$	312		$	(81	)	$	231
Reclassification adjustment for amounts related to available-for-sale investments included in net income (loss)		1,416			(368	)		1,048			(62	)		16			(46	)
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income (loss)		204			(63	)		141			175			(54	)		121
Foreign currency translation adjustment		(1,650	)		—			(1,650	)		(1,160	)		—			(1,160	)
Total Other Comprehensive Loss	$	(1,288	)	$	(104	)	$	(1,392	)	$	(735	)	$	(119	)	$	(854	)

A summary of the calculation of basic and diluted earnings (loss) per share for the three months ended March 31, ~~2019~~2020 and ~~2018~~2019 is as follows:

	Three Months Ended					Three Months Ended
	March 31,					March 31,
(In thousands, except per share amounts)	2019		2018			2020			2019
Numerator
Net income (loss)	$	770	$	(10,814	)	$	(9,969	)	$	770
Denominator
Weighted average number of shares – basic		47,782		48,232			47,957			47,782
Effect of dilutive securities
Stock options		—		—
PSUs, RSUs and restricted stock		71		—			—			71
Weighted average number of shares – diluted		47,853		48,232			47,957			47,853
Earnings (loss) per share – basic	$	0.02	$	(0.22	)	$	(0.21	)	$	0.02
Earnings (loss) per share – diluted	$	0.02	$	(0.22	)	$	(0.21	)	$	0.02

For the three months ended March 31, 2020, 0.4 million shares of unvested PSUs, RSUs and restricted stock were excluded from the calculation of diluted earnings per share due to their anti-dilutive effect.

For the three months ended March 31, 2020 and 2019, 5.9 million and ~~2018,~~ 2.9 million ~~and 4.8 million~~ stock options, respectively, were outstanding but were not included in the computation of diluted earnings ~~(loss)~~ per ~~share~~share. These stock options were excluded because ~~the stock options’~~their exercise prices were greater than the average market price of the common shares during the quarter, therefore making them anti-dilutive under the treasury stock method.

~~We operate in two~~The chief operating decision maker regularly reviews the Company’s financial performance based on 2 reportable segments: (1) Network Solutions and (2) Services & Support. Network Solutions includes hardware ~~products~~ and software ~~defined~~products and next-generation virtualized solutions used in service provider or business networks, as well as prior-generation products. Services & Support includes ~~our suite~~a portfolio of ~~ProCloud managed services,~~maintenance, network installation ~~engineering~~ and ~~maintenance~~solution integration services, which include hosted cloud services and ~~fee-based technical support and equipment repair/replacement plans.~~subscription services.

~~We evaluate the~~The performance of our segments is evaluated based on gross profit; therefore, selling, general and administrative expenses, research and development expenses, interest and dividend income, interest expense, net investment gain (loss), other income (expense) and (provision) benefit for income taxes are reported on a company-wide ~~functional~~ basis only. There is no inter-segment revenue. Asset information by reportable segment is not produced and, therefore, is not reported.

The following table presents information about the ~~reported~~ sales and gross profit of our reportable segments for the three months ended March 31, ~~2019~~2020 and ~~2018. We do not produce asset information by reportable segment; therefore, it is not reported.~~2019.

	Three Months Ended
	March 31,								Three Months Ended
	2019				2018				March 31, 2020				March 31, 2019
(In thousands)	Sales		Gross Profit		Sales		Gross Profit		Sales		Gross Profit		Sales		Gross Profit
Network Solutions	$	125,822	$	55,088	$	105,253	$	36,641	$	97,372	$	45,746	$	125,822	$	55,088
Services & Support		17,969		5,524		15,553		3,092		17,151		5,854		17,969		5,524
Total	$	143,791	$	60,612	$	120,806	$	39,733	$	114,523	$	51,600	$	143,791	$	60,612

In addition to our reporting segments, werevenue is also ~~report revenue~~reported for the following ~~three~~3 categories – Access & Aggregation, Subscriber Solutions & Experience ~~(formerly Customer Devices)~~ and Traditional & Other Products.

The table below presents sales information by category for the three months ended March 31, ~~2019~~2020 and ~~2018:~~2019:

	Three Months Ended				Three Months Ended
	March 31,				March 31,
(In thousands)	2019		2018		2020		2019
Access & Aggregation	$	99,778	$	81,680	$	65,966	$	99,778
Subscriber Solutions & Experience		36,753		30,101		42,179		36,753
Traditional & Other Products		7,260		9,025		6,378		7,260
Total	$	143,791	$	120,806	$	114,523	$	143,791

The following table ~~represents~~presents sales information by geographic area for the three months ended March 31, ~~2019~~2020 and ~~2018:~~2019:

	Three Months Ended				Three Months Ended
	March 31,				March 31,
(In thousands)	2019		2018		2020		2019
United States	$	72,528	$	62,086	$	78,991	$	72,528
International		71,263		58,720		35,532		71,263
Total	$	143,791	$	120,806	$	114,523	$	143,791

Our products generally include warranties of 90 days to five years for product defects. ~~We accrue for warranty~~Warranty returns are accrued at the time revenue is recognized based on ~~our~~an estimate of the cost to repair or replace the defective products. We engage in extensive product quality programs and processes, including actively monitoring and evaluating the quality of our component suppliers. ~~Our products~~Products continue to become more complex in both size and functionality as many of our product offerings migrate from line card applications to total systems. The increasing complexity of ~~our~~ products will cause warranty incidences, when they arise, to be more costly. ~~Our estimates~~Estimates regarding future warranty obligations may change due to product failure rates, material usage and other rework costs incurred in correcting a product failure. In addition, from time to time, specific warranty accruals may be recorded if unforeseen problems arise. Should ~~our~~ actual experience relative to these factors be worse than ~~our estimates, we~~estimated, additional warranty expense will be ~~required to record additional warranty expense.~~incurred. Alternatively, if ~~we provide for more reserves~~actual costs incurred are less than ~~we require, we will reverse~~estimated, a portion of ~~such provisions~~the warranty reserves will be reversed in future periods. The liability for warranty obligations totaled ~~$8.8~~$7.6 million and ~~$8.6~~$8.4 million atas of March 31, ~~2019~~2020 and December 31, ~~2018, which~~2019, respectively, and are included in accrued expenses and other liabilities in the accompanying Condensed Consolidated Balance ~~Sheet.~~Sheets. During the three months ended March 31, 2020, we had a reversal of prior provisions related to warranty expirations, the impact of which is reflected in the table below.

A ~~summary~~reconciliation of warranty expense and related write-off activity for the three months ended March 31, ~~2019~~2020 and ~~2018~~2019 is as follows:

	Three Months Ended						Three Months Ended
	March 31,						March 31,
(In thousands)	2019			2018			2020			2019
Balance at beginning of period	$	8,623		$	9,724		$	8,394		$	8,623
Plus: Amounts charged to cost and expenses		1,131			1,822			(55	)		1,131
Less: Deductions		(952	)		(1,859	)		(704	)		(952	)
Balance at end of period	$	8,802		$	9,687		$	7,635		$	8,802

On October 17, 2019, a purported stockholder class action lawsuit, captioned Burbridge v. ADTRAN, Inc. et al., Docket No. 19-cv-09619, was filed in the United States District Court for the Southern District of New York against the Company, 2 of its current executive officers and 1 of its former executive officers. The complaint alleges violations of federal securities laws and seeks unspecified compensatory damages on behalf of purported purchasers of ADTRAN securities between February 28, 2019 and October 9, 2019. The lawsuit claims that the defendants made materially false and misleading statements regarding, and/or failed to disclose material adverse facts about, the Company’s business, operations and prospects, specifically relating to the Company’s internal control over financial reporting, excess and obsolete inventory reserves, financial results and demand from certain customers. The lawsuit was transferred to the U.S. District Court for the Northern District of Alabama on January 7, 2020, and co-lead plaintiffs have been appointed to represent the putative class. The plaintiffs filed an amended complaint on April 30, 2020. The defendants intend to file a motion to dismiss the amended complaint. We deny the allegations in the complaint, as amended, and intend to vigorously defend against this lawsuit. At this time, we are unable to predict the outcome of or estimate the possible loss or range of loss, if any, associated with this lawsuit.

On March 31, 2020, a shareholder derivative suit, captioned Johnson (Derivatively on behalf of ADTRAN) v. T. Stanton, M. Foliano, R. Shannon, and Board of Directors, case no. 5:20-cv-00447, was filed in the U.S. District Court of Northern Alabama against 2 of the Company’s current executive officers, 1 of its former executive officers and its Board of Directors. The derivative suit, which is purportedly brought on behalf of ADTRAN, makes similar allegations as the shareholder class action and accuses the directors and officers of breaches of fiduciary duty in connection with those allegations. The Company expects that the derivative lawsuit will be stayed by the Court pending resolution of the class action. The Company and its defendants disagree with the claims made in the complaint, and the defendants intend to vigorously defend against this lawsuit. At this time, we are unable to predict the outcome of or estimate the possible loss or range of loss, if any, associated with this lawsuit.

In addition to the ~~ordinary course of business,~~litigation described above, from time to time we ~~may be~~are subject to or otherwise involved in various lawsuits, claims, investigations and legal proceedings that arise out of or are incidental to the conduct of our business (collectively, “Legal Matters”), including those relating to employment matters, patent rights, regulatory compliance matters, stockholder claims, and ~~claims, including employment disputes, patent claims, disputes over contract agreements~~contractual and other commercial disputes. ~~In some cases,~~Such Legal Matters, even if not meritorious, could result in the expenditure of significant financial and managerial resources. Additionally, an unfavorable outcome in any legal matter, including in a patent dispute, could require the Company to pay damages, entitle claimants ~~seek damages or~~to other relief, such as ~~royalty payments related to patents,~~royalties, or could prevent the Company from selling some of its products in certain jurisdictions. While the Company cannot predict with certainty the results of the Legal Matters in which ~~if granted, could require significant expenditures. Although~~it is currently involved, the Company does not expect that the ultimate outcome of ~~any claim~~such Legal Matters will individually or ~~litigation can never be certain, it is our opinion that~~in the ~~outcome~~aggregate have a material adverse effect on its business, results of ~~all contingencies of which we are currently aware will not materially affect our business,~~ operations, financial condition or cash flows.

Certain contracts, customers and/or jurisdictions in which we do business require us to provide various guarantees of performance such as bid bonds, performance bonds and customs bonds. As of March 31, 2020 and December 31, 2019, we had commitments related to these bonds totaling $7.6 million and $9.3 million, respectively, which expire at various dates through August 2024. Although the triggering events vary from contract to contract, in general we would only be liable for the amount of these guarantees in the event of default under each contract, the probability of which we believe is remote.

We have committed to invest up to an aggregate of $7.9 million in ~~two~~2 private equity funds, ~~and we have contributed $8.4 million as of March 31, 2019,~~ of which $7.7 million has been applied ~~to these commitments.~~as of March 31, 2020

Under ASC 326 – Financial Instruments – Credit Losses, the Company estimates credit losses for the contractual life of assets that are measured at amortized cost and are within the scope of this guidance, which included its account receivable, net investment in sales-type leases, contract assets under the revenue recognition model and outstanding note receivable. Where appropriate, the Company pooled assets if similar risk characteristics existed. Additionally, the Company analyzed its available-for-sale debt securities to determine if any were impaired and, therefore, a credit loss was needed.

The Company records accounts receivable in the normal course of business as products are shipped or services are performed and invoiced, but payment has not yet been remitted by the customer. As of January 1, 2020 and March 31, 2020, the Company’s outstanding accounts receivable balance was $90.5 million and $86.5 million, respectively. The Company assessed the need for an allowance for credit losses related to its outstanding accounts receivable using the historical loss-rate method as well as assessing asset-specific risks. The Company’s historical losses related to accounts receivable have been immaterial as evidenced by its historical allowance and write-offs due to uncollectability. The assessment of asset-specific risks included the evaluation of relevant available information, from internal and external sources, relating to current conditions that may affect a customer’s ability to pay, such as the customer’s current financial condition, credit rating by geographic location, as provided by a third party and/or by customer, if needed, and overall macro-economic conditions in which the customer operates. The Company pooled assets by geographic location to determine if an allowance should be applied to its accounts receivable balance, assessing the specific country risk rating and overall economics of that particular country. If elevated risk existed, or customer specific risk indicated the accounts receivable balance was at risk, the Company further analyzed the need for an allowance related to specific accounts receivable balances. Additionally, the Company determined that significant changes to customer country risk rating from period-to-period and from the end of the prior year to the end of the current quarter would require further review and analysis by the Company.

Accounts receivable balances are considered past due when payment has not been received by the date indicated on the relevant invoice or based on agreed upon terms between the customer and the Company.

NaN allowance for credit loss was recorded on January 1, 2020 (the “implementation date”) or during the three months ended March 31, 2020 related to accounts receivable. The Company’s allowance for credit losses related to accounts receivable was $38 thousand as of March 31, 2020 and December 31, 2019, all of which was expensed prior to January 1, 2020.

The Company records contract assets when it has recognized revenue but has not yet billed the customer. As of January 1, 2020 and March 31, 2020, the Company’s outstanding contract asset balance was $2.8 million and $1.4 million, respectively, which is included in other receivables on the Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019. The Company assessed the need for an allowance for credit losses related to its outstanding contract assets using the historical loss-rate method as well as asset-specific risks. The Company’s historical losses related to contract assets receivable have been immaterial as evidenced by historical write-offs due to uncollectability. Asset-specific risk included the evaluation of relevant available information, from internal and external sources, relating to current conditions that may affect a customer’s ability to pay once invoiced, such as the customer’s financial condition, credit rating by geographic location as provided by a third party and/or by customer, if needed, and overall macro-economic conditions in which the customer operates. The Company pooled assets by geographic location to determine if an allowance should be applied to its contract asset balance, assessing the specific country risk rating and overall economics of that particular country. If elevated risk existed, or customer specific risk indicated the contract balance was at risk, the Company further analyzed the need for an allowance related to specific customer balances. Additionally, the Company determined that significant changes to customer country risk rating from period-to-period and from the end of the prior year to the end of the current quarter would require further review and analysis by the Company.

NaN allowance for credit loss was recorded on the implementation date or during the three months ended March 31, 2020 related to contract assets.

The Company is the lessor in sales-type lease arrangements for network equipment. As of January 1, 2020 and March 31, 2020, the Company’s outstanding net investment in sales-type leases was $1.6 million and $1.3 million, respectively, which is included in other receivables and other assets on the Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019. The Company assessed the need for an allowance for credit losses related to future receivables under its outstanding sales-type leases using the historical loss-rate method as well as asset-specific risks. The Company’s historical losses related to contract assets receivable have been immaterial as evidenced by historical write-offs due to uncollectability. Asset-specific risk included the evaluation of relevant available information, from internal and external sources, relating to current conditions that may affect a customer’s ability to pay once invoiced, such as the customers financial condition, credit rating by geographic location as provided by a third party and/or by customer, if needed, and overall macro-economic conditions in which the customer operates.

The following table presents amortized cost basis in sales-type leases based on payment activity:

	Sales-Type Leases Amortized Cost Basis by Origination Year
(In thousands)	2020		2019		2018		2017		2016		Prior		Total
Payment performance
Performing	$	36	$	294	$	582	$	231	$	165	$	34	$	1,342
Non-performing		—		—		—		—		—		—		—
Total	$	36	$	294	$	582	$	231	$	165	$	34	$	1,342

Sales-type lease receivables are considered past due when payment has not been received based on agreed upon terms between the customer and the Company. NaN allowance for credit loss was recorded on the implementation date or during the three months ended March 31, 2020 related to sales-type leases.

The Company has a secured loan receivable totaling $0.9 million as of March 31, 2020 and January 1, 2020, which originated in February 2019, and is included in long-term investments on the Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019. The Company assessed the need for an allowance for credit loss related to its secured loan receivable using the historical loss-rate method as well as asset-specific risks. The Company’s historical losses related to this receivable have been $0. Asset-specific risks included the evaluation of relevant available information, from internal and external sources, relating to current conditions that may affect the customer’s ability to repay the loan upon maturity, such as the customer’s current financial condition, credit rating specific to the customer as determined by a third party and current overall economic conditions, as well as a company valuation prepared by a third party which was based on reasonable and supportable forecasts as provided by management. Accrued interest receivable on the secured loan receivable, which is included in other receivables on the Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019, totaled $24 thousand and $41 thousand as of January 1, 2020 and March 31, 2020, respectively, and was excluded from the estimate of credit losses for both periods based on the Company’s accounting policy election.

NaN allowance for credit loss was recorded on the implementation date or during the three months ended March 31, 2020 related to the secured loan receivable.

The Company did not have any off-balance sheet arrangements as of January 1, 2020 or March 31, 2020.

As of January 1, 2020 and March 31, 2020, the Company’s available-for-sale debt securities totaled $37.7 million and $37.9 million, respectively. These securities were analyzed at the individual investment level, by CUSIP, to limit credit losses, if applicable, to reflect only the amount by which the fair value of the security was less than its amortized cost. The Company noted that, as of January 1, 2020 and March 31, 2020, there was no intent to sell any of its available-for-sale debt securities before maturity and therefore, the Company assessed the need for an allowance for each of its available-for-sale debt securities in which the fair value was less than its amortized cost as of January 1, 2020 and March 31, 2020. Accrued interest receivable on available-for-sale debt securities, which is included in other receivables on the Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019, totaled $0.1 million as of January 1, 2020 and March 31, 2020, and was excluded from the estimate of credit losses for both periods based on the Company’s accounting policy election.

The following table outlines the available-for-sale debt securities in an unrealized loss position as of January 1, 2020:

(In thousands)	Continuous Unrealized Loss Position for Less than 12 Months					Continuous Unrealized Loss Position for 12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate bonds		203		—			—		—			203		—
Municipal fixed-rate bonds		930		—			—		—			930		—
Asset-backed bonds		797		(3	)		—		—			797		(3	)
Mortgage/Agency-backed bonds		2,594		(6	)		136		(2	)		2,730		(8	)
U.S. government bonds		4,070		(9	)		—		—			4,070		(9	)
Total	$	8,594	$	(18	)	$	136	$	(2	)	$	8,730	$	(20	)

The Company had 60 positions in available-for-sale debt securities that were in an unrealized loss position as of March 31, 2020, which are presented in the table below:

(In thousands)	Continuous Unrealized Loss Position for Less than 12 Months					Continuous Unrealized Loss Position for 12 Months or Greater				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds		4,166		(87	)		—		—		4,166		(87	)
Municipal fixed-rate bonds		—		—			—		—		—		—
Asset-backed bonds		3,901		(76	)		—		—		3,901		(76	)
Mortgage/Agency-backed bonds		1,577		(62	)		—		—		1,577		(62	)
U.S. government bonds		1,242		(6	)		—		—		1,242		(6	)
Total	$	10,886	$	(231	)	$	—	$	—	$	10,886	$	(231	)

For those available-for-sale debt securities whose fair value was less than its amortized cost basis, the Company analyzed additional criteria such as adverse conditions specifically related to the security, an industry or geographic area, failure of the issuer of the security to make scheduled interest or principal payments, if applicable, and any changes to the rating of the security by a rating agency to determine if a credit loss existed. The Company used information provided by its investment manager to determine if any scheduled interest or principal payments had not been received and used a third party to determine if any changes to credit ratings had occurred. The Company noted that all principal and interest payments had been received as scheduled and that there had been no changes in credit ratings year-over-year or period-over-period that warranted further review.

NaN allowance for credit loss was recorded on the implementation date or during the three months ended March 31, 2020 related to the Company’s available-for-sale debt securities.

During the second half of 2019, the Company implemented a restructuring plan to realign its expense structure with the reduction in revenue experienced in recent years and overall Company objectives. Management assessed the efficiency of operations and, in turn, consolidated locations and personnel, among other things, where possible. As part of this restructuring plan, the Company announced plans to reduce its overall operating expenses, both in the U.S. and internationally.

In February 2019, wethe Company announced the restructuring of certain of our workforce predominantly in Germany, which included the closure of ~~the~~our office location in Munich, Germany accompanied by relocation or severance benefits for the affected employees. The restructuring is expected to be completed in the fourth quarter of 2019. The cumulative amount incurred during the three months ended March 31, 2019 related to this restructuring program is $1.8 million. We also offered a voluntaryVoluntary early retirement ~~offering~~was offered to certain other employees, which was announced ~~to employees~~ in March 2019. ~~As of March 31, 2019, we did not have sufficient information on which to estimate an additional liability associated with the voluntary early retirement program.~~

In January 2018, we announced an early retirement incentive program for employees that met certain requirements. The cumulative amount incurred during the year ended December 31, 2018 related to this restructuring program was $7.3 million, of which $6.0 million was incurred during the three months ended March 31, 2018. We do not expect to incur any additional expenses related to this restructuring program.

A reconciliation of the beginning and ending restructuring liability, which is included in accrued wages and benefits onin the Consolidated Balance ~~Sheet,~~Sheets as of March 31, 2020 and December 31, 2019, is as follows:

Restructuring expenses included in the Condensed Consolidated Statements of Income (Loss) were as follows:

The following table represents the components of restructuring expense ~~in the Consolidated Statements of Income are as follows:~~

On ~~April 17, 2019,~~May 6, 2020, we announced that our Board of Directors declared a quarterly cash dividend of $0.09 per common share to be paid to the Company’s stockholders of record atas of the close of business on May ~~2, 2019.~~21, 2020. The payment date will be ~~May 16, 2019. The quarterly dividend payment will be~~June 4, 2020 in the aggregate amount of approximately $4.3 million. ~~In July 2003, our Board of Directors elected to begin declaring quarterly dividends on our common stock considering the tax treatment of dividends and adequate levels of Company liquidity.~~

A voluntary early retirement offering was communicated to certain of our employees in Germany in March 2019. These employees were given until April 28, 2019 to accept the early retirement offering. Therefore, as of March 31, 2019, we did not have sufficient information on which to estimate the liability associated with this program. The Company expects to incur approximately $0.8 million in restructuring expense during the second quarter of 2019 related to the early retirement program.

ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion should be read in conjunction with the ~~Consolidated Financial Statements~~consolidated financial statements and the related notes that appear in Part I, Item 1 of this document. In addition, the following discussion should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2019, Part II, Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations, Part I, Item 1, Business, and Item 1A, Risk Factors, included in our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 25, 2020 (the “2019 Form 10-K”).

This discussion is designed to provide the reader with information that will assist in understanding our condensed consolidated financial statements, the changes in certain key items in those financial statements from period to period, and the primary factors that accounted for those changes, as well as how certain accounting principles affect our condensed consolidated financial statements. See “Cautionary Note Regarding Forward-Looking Statements” on page 3 of this report for a description of important factors that could cause actual results to differ from expected results. See also Part 1, Item 1A, Risk Factors, of the 2019 Form 10‑K and Part II, Item 1A, Risk Factors, of this Form 10-Q.

ADTRAN is a leading global provider of networking and communications equipment, serving a diverse domestic and international customer base in 68multiple countries that includes Tier-1, 2-2 and 3-3 service providers, ~~Cable/~~cable/MSOs and distributed enterprises. Our innovative solutions and services enable voice, data, video and internet communications across a variety of network infrastructures and are currently in use by millions worldwide. We support our customers through our direct global sales organization and our distribution networks. Our success depends upon our ability to increase unit volume and market share through the introduction of new products and succeeding generations of products having lower selling prices and increased functionality as compared to both the prior generation of a product and to the products of competitors. In order to service our customers and ~~build~~grow revenue, we are constantly conducting research and development ~~(R&D)~~ of new products addressing customer needs and testing those products for the particular specifications of the particular customers. ~~In addition to our corporate headquarters in Huntsville, Alabama, we have R&D facilities in strategic global locations.~~

We are focused on being a top global supplier of access infrastructure and related value-added solutions from the cloud edge to the subscriber edge. We offer a broad portfolio of flexible software and hardware network solutions and services that enable service providers to meet today’s service demands, while enabling them to transition to the fully-converged, scalable, highly-automated, cloud-controlled voice, data, internet and video network of the future. In addition to our corporate headquarters in Huntsville, Alabama, we have research and development facilities in strategic global locations.

An important part of our strategy is to reduce the cost of each succeeding product generation and then lower the product’s selling price based on the cost savings achieved in order to gain market share and/or improve gross margins. As a part of this strategy, we seek to be a high-quality, and in most instances the low-cost, provider of products in our markets. Our success to date is attributable in large measure to our ability to design our products initially with a view to their subsequent redesign, allowing both increased functionality and reduced manufacturing costs in each succeeding product generation. This strategy enables us to sell succeeding generations of products to existing customers, while increasing our market share by selling these enhanced products to new customers.

Our business is global. We supply different sets of products to different customers in different regions around the world. Our financial results in any period reflect the activities of our various customers in their respective regions at any given time. The lead times to revenue for new products vary.

~~The Company made two acquisitions in 2018, strengthening its position in both the Cable/MSO and connected home markets. In~~While we ended the first quarter of ~~2018,~~ 2020 with a year-over-year revenue decrease of 20.4%, we ~~acquired~~continued to have good geographical diversity with 31.0% of our revenue coming from international markets. Additionally, we had three 10% revenue customers geographically diversified with two in the ~~market-leading EPON~~U.S and one in Europe. Our domestic revenue grew 8.9% during the three months ended March 31, 2020 compared to the same quarter in the prior year, which was driven by an increase in sales to RSPs and additional fiber deployments across all customers. In addition, we saw an increase in sales to a Tier-1 customer with diversified business among our fiber access and CPE, service provider CPE and services as well as sales to Tier-3 customers. In Europe, we saw an increase in revenue from a Tier-1 customer as its spending increased after a slow-down in spending during the second half of 2019. Additionally, the same Tier-1 customer continued expansion of its vectoring and super-vectoring VDSL2 solutions and we experienced continued increases in our service provider CPE business during the three months ended March 31, 2020.

During the first quarter of 2020, there was a downturn in the global financial markets and a slowdown in the global economy due to the COVID-19 pandemic. In March 2020, the World Health Organization declared the outbreak of COVID-19 a pandemic. COVID-19 continues to spread throughout the U.S. and the world and has resulted in authorities implementing numerous measures to contain the virus, including travel bans and restrictions, quarantines, shelter-in-place orders, and business limitations and shutdowns. While we are unable to accurately predict the full impact that COVID-19 will have on our results from operations, financial condition, liquidity and cash flows due to numerous uncertainties, including the duration and severity of the pandemic and containment measures, our compliance with these measures has impacted our day-to-day operations and could disrupt our business and ~~certain assets~~operations, as well as that of our key customers, suppliers and other counterparties, for ~~North America from Sumitomo~~ an indefinite period of time. We have experienced some impact to our supply chain, including a slow-down in supply chain deliveries and some raw material and freight-related cost increases. Additionally, COVID-19 had some impact on our financial results for the first quarter. In the early stages of the downturn, we have seen increased demand in networking requirements and utilization due to social distancing guidelines issued by governments. While we expect that we may experience some slow-down in demand and potential supply-chain issues, as the pandemic continues, we do not at this time expect the overall impact of COVID-19 to materially impact our operations, results of operations and cash flows.

~~Electric Industries Ltd. These solutions, combined~~Among our customers, we made progress with our ~~organic~~ fiber ~~access product portfolio~~ and fiber-extension solutions, including Gfast and PON, while also continuing to engage various Services & Support opportunities that we expect will contribute in 2020 and beyond. In addition, we believe we are at the beginning of a significant investment cycle for fiber deployment driven by technology advancements, regulatory influences and vendor disruption. The transition to next-generation network architectures is beginning, and we are seeing demand for our ~~distributed access expertise, present new opportunities in~~next-generation SD-Access solutions. In the ~~Cable/MSO market. Also, in~~latter part of 2020, we anticipate that payments to service providers under government funding programs such as the fourth quarter of 2018, we acquired U.S.-based SmartRG, an industry-leading provider of carrier-class, connected–home software platforms and cloud services for broadband service providers. With this acquisition, ADTRAN now offers a complete cloud-to-consumer portfolio of virtualized management, data analytics, Wi-Fi-enabled residential gateways and software platforms. FCC Rural Digital Opportunity Fund will begin.~~For more information, see Note 2 of the Notes to Consolidated Financial Statements included in Item 1 of this report.~~

~~We review~~In addition to classifying our ~~financial performance, specifically revenue and gross profit, based on~~operations into two reportable segments, – Network Solutions and Services & Support. Network Solutions software and hardware products provide solutions supporting fiber-, copper- and coaxial-based infrastructures and a growing number of wireless solutions, lowering the overall cost to deploy advanced services across a wide range of applications for Carrier, Cable/MSO networks and business networks, as well as for prior-generation products. Our Services & Support enables our customers to accelerate time to market, reduce costs and improve customer satisfaction through a complete portfolio of services, including maintenance, turnkey network implementation, solutions integration, and managed services. ADTRAN’s comprehensive network implementation services include engineering design and documentation (pre-construction), construction and installation (construction), and test, turn-up and provisioning (post-construction). Additionally, we ~~partner with customers to tailor a program to each specific service-delivery need.~~

We report revenue ~~for the following~~across three categories of products and services – (1) Access & Aggregation, (2) Subscriber Solutions & Experience ~~(formerly Customer Devices)~~ and (3) Traditional & Other ~~Products.~~Products.

Our Access & Aggregationsolutions are used by ~~service providers~~CSPs to connect their network infrastructure to ~~their~~ subscribers. This revenue category includes ~~software-~~hardware- and ~~hardware-based~~software-based products and services that aggregate and/or originate access technologies. ~~The portfolio of~~ ADTRAN solutions within this category ~~includes~~include a wide array of modular or fixed ~~physical form factors~~platforms designed to deliver the best technology and ~~economic fit~~economy based on ~~the target~~ subscriber density and environmental conditions.

Our Subscriber Solutions & Experience ~~(formerly Customer Devices) includes open-source connected home platforms, cloud services and any of our solutions and services that deliver residential and/or enterprise subscribers~~portfolio is used by service providers to terminate their infrastructure at the customer’s premises while providing an immersive and interactive ~~broadband~~ experience ~~from~~for the ~~service provider’s~~subscriber. These solutions include copper and fiber WAN termination, LAN switching, Wi-Fi access, ~~network. These products,~~and cloud software ~~and~~ services, ~~include SmartRG solutions and applications, NetVanta Enterprise IP business gateways, access routers, Ethernet switches, ProCloud service offerings,~~for both residential and enterprise operating systems (such as SmartOS and AOS), Bluesocket Wi-Fi portfolio, service provider and Cable/MSO Optical Network Terminals (ONTs), as well as related software applications and services. In alignment with our increased focus on enhancing customer experience for both business and consumer broadband customers as well as the addition of SmartRG during 2018, Customer Devices is now known as Subscriber Solutions & Experience, as this more accurately represents this revenue category and our vision moving forward.markets.

Our Traditional & Other Products category generally includes a mix of ~~prior generation~~prior-generation technologies’ products and services, as well as other products and services that do not fit within the ~~Access & Aggregation or Subscriber Solutions & Experience categories.~~

~~See Note 15 of Notes to Consolidated Financial Statements in Item 1 of this Form 10-Q for further information regarding these product~~other revenue categories.

Our operating results have fluctuated, and may continue to fluctuate, on a quarterly basis ~~in the past, and may vary significantly in future periods,~~ due to a number of factors, including customer order activity and backlog. ~~Backlog~~A substantial portion of our shipments in any fiscal period relates to orders received and shipped within that fiscal period for customers under agreements containing non-binding purchase commitments. Further, a significant percentage of orders require delivery within a few days. These factors normally result in a varying order backlog and limited order flow visibility. Additionally, backlog levels may vary because of seasonal trends, the timing of customer projects, and other factors that affect customer order lead times. ~~Many~~Because many of our customers require prompt delivery of ~~products. This requires us~~products, we are required to maintain sufficient inventory levels to satisfy anticipated customer demand. If near-term demand for our products declines, or if potential sales in any quarter do not occur as anticipated, our financial results could be adversely affected. Operating expenses are relatively fixed in the short term; therefore, a shortfall in quarterly ~~revenue~~revenues could significantly impact our financial results in a given quarter.

Our operating results may also fluctuate as a result of a number of other factors, including a decline in general economic and market conditions, specifically the decline that has resulted from the COVID-19 pandemic, foreign currency exchange rate movements, increased competition, customer order patterns, changes in product and services mix, timing differences between price decreases and product cost reductions, product warranty returns, expediting costs, tariffs and announcements of new products by us or our competitors. Additionally, maintaining sufficient inventory levels to assure prompt delivery of our products increases the amount of inventory that may become obsolete and increases the risk that the obsolescence of this inventory may have an adverse effect on our business and operating results. Also, not maintaining sufficient inventory levels to assure prompt delivery of our products may cause us to incur expediting costs to meet customer delivery requirements, which may negatively impact our operating results in a given quarter. During 2019, the Company implemented restructuring plans to realign its expense structure with the reduction in revenue experienced in recent years and with overall Company objectives. Management assessed the efficiency of our operations and consolidated locations and personnel, among other things, and has implemented certain cost savings initiatives, where possible. We expect to continue to see a reduction in our operating expenses, both in the U.S. and internationally, as a result of our implementation of these restructuring plans.

~~Accordingly, our~~Our historical financial performance is not necessarily a meaningful indicator of future results, and in general, management expects that our financial results may vary from period to period. Factors that could materially affect our business, financial condition or operating results are included in Part I, Item 1A of ~~Part I in our most recent Annual Report on~~the 2019 Form 10-K ~~for the year ended December 31, 2018, filed on February 28, 2019, with the SEC~~ and in Part II, Item 1A ~~herein.~~of this Form 10-Q.

~~Our~~There have been no material changes to our critical accounting policies and estimates ~~have not changed significantly~~ from those ~~detailed~~disclosed in our ~~most recent Annual Report on~~2019 Form ~~10-K for the year ended December 31, 2018, filed on February 28, 2019, with the SEC.~~10-K.

See Note 1 of the Notes to Condensed Consolidated Financial Statements included in Part I, Item 1 of this ~~Form 10-Q~~report for a full description of recent accounting pronouncements, including the expected dates of adoption and estimated effects on results of operations and financial condition, which is incorporated herein by reference.

RESULTS OF OPERATIONS – THREE MONTHS ENDED MARCH 31, ~~2019~~2020 COMPARED TO THREE MONTHS ENDED MARCH 31, ~~2018~~2019

The following table presents selected financial information derived from our Condensed Consolidated Statements of Income (Loss) expressed as a percentage of sales for the ~~quarters~~periods indicated. Amounts may not foot due to rounding.

	Three Months Ended								Three Months Ended
	March 31,								March 31,
	2019				2018				2020				2019
Sales
Products		87.5		%		87.1		%
Services		12.5				12.9
Network Solutions										85.0		%		87.5		%
Services & Support										15.0				12.5
Total Sales		100.0				100.0				100.0				100.0
Cost of Sales
Products		49.2				56.8
Services		8.7				10.3
Network Solutions										45.1				49.2
Services & Support										9.9				8.7
Total Cost of Sales		57.8				67.1				54.9				57.8
Gross Profit		42.2				32.9				45.1				42.2
Selling, general and administrative expenses		24.4				27.8				23.2				24.4
Research and development expenses		22.0				27.2				26.1				22.0
Operating Income		(4.3	)			(22.1	)
Asset impairments										0.1				—
Operating Loss										(4.3	)			(4.3	)
Interest and dividend income		0.4				0.7				0.3				0.4
Interest expense		(0.1	)			(0.1	)			—				(0.1	)
Net investment gain (loss)		4.1				(0.1	)			(9.5	)			4.1
Other income (expense), net		0.6				—
Gain on bargain purchase of a business, net		—				9.4
Income (Loss) Before Provision for Income Taxes		0.7				(12.2	)
(Provision) benefit for income taxes		(0.2	)			3.3
Other income, net										1.0				0.6
Income (Loss) Before Income Taxes										(12.5	)			0.7
Income tax (expense) benefit										3.8				(0.2	)
Net Income (Loss)		0.5		%		(9.0	)	%		(8.7	)	%		0.5		%

Our sales ~~increased 19.0%~~decreased 20.4% from ~~$120.8~~$143.8 million infor the three months ended March 31, ~~2018~~2019 to ~~$143.8~~$114.5 million infor the three months ended March 31, ~~2019.~~2020. The ~~increase~~decrease in sales for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to ~~an $18.1~~a $33.8 million ~~increase~~decrease in Access & Aggregation ~~products,~~sales and a ~~$6.7 million increase in sales of our Subscriber Solutions & Experience products, partially offset by a $1.8~~$0.9 million decrease in sales of our Traditional & Other ~~products.~~Products, partially offset by a $5.4 million increase in Subscriber Solutions & Experience sales.

Network Solutions segment sales ~~increased 19.5%~~decreased 22.6% from ~~$105.3~~$125.8 million infor the three months ended March 31, ~~2018~~2019 to ~~$125.8~~$97.4 million infor the three months ended March 31, ~~2019.~~2020. The ~~increase~~decrease in sales for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to ~~an increase~~the slowdown in shipments to two Tier-1 customers. For the three months ended March 31, 2020, sales ofin the Access & Aggregation ~~products~~ and Traditional & Other Products categories decreased, partially offset by an increase in Subscriber Solutions & Experience ~~products, partially offset by a~~category sales. The decrease in ~~sales of our Traditional & Other products. The increase in sales of our~~ Access & Aggregation ~~products~~sales for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to decreased sales of FTTN products. The increase in Subscriber Solutions & Experience sales for the three months ended March 31, 2020 was primarily attributable to increased ~~fiber to the premises (FTTN) products, Gfast distribution point units (DPUs) and fiber access and aggregation. The increase in~~ sales of ~~our Subscriber Solutions & Experience is primarily attributable to increased fiber~~SP Business CPE Network Termination and ~~network termination.~~Fiber CPE. While we expect that revenue from Traditional & Other Products will continue to decline over time, this revenue may fluctuate and continue for years because of the time required for our customers to transition to newer technologies.

Services & Support segment sales ~~increased 15.5%~~decreased 4.6% from ~~$15.6~~$18.0 million infor the three months ended March 31, ~~2018~~2019 to ~~$18.0~~$17.2 million infor the three months ended March 31, ~~2019.~~2020. The ~~increase~~decrease in sales for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to ~~an increase~~a decrease in ~~network installation~~maintenance services for Access & Aggregation products.

International sales, which are included in the amounts for both the Network Solutions and Services & Support ~~amounts~~segments discussed above, ~~increased 21.4%~~decreased 50.1% from ~~$58.7~~$71.3 million infor the three months ended March 31, ~~2018~~2019 to ~~$71.3~~$35.5 million infor the three months ended March 31, ~~2019.~~2020. International sales, as a percentage of total sales, ~~increased~~decreased from ~~48.6% for the three months ended March 31, 2018 to~~ 49.6% for the three months ended March 31, ~~2019.~~2019 to 31.0% for the three months ended March 31, 2020. The ~~increase~~decrease in sales for the three months ended March 31, ~~2019 is~~2020, was primarily attributable the slowdown in shipments to ~~an increase in sales in LATAM and APAC regions. The increase in sales in LATAM for the three months ended March 31, 2019 is primarily attributable to a network expansion program of a large~~two international Tier-1 ~~customer. The increase in sales in APAC for the three months ended March 31, 2019 is primarily attributable to a network expansion program in Australia.~~customers.

Our international revenue is largely focused on broadband infrastructure and is ~~effected~~affected by the decisions of our customers as to timing for installation of new technologies, expansion of their networks and/or network upgrades. Our international customers must make these decisions in the regulatory and political environment in which they operate – both nationally and in some instances, regionally – whether of a multi-country region or a more local region within a country. For example, the European Commission launched a Gigabit Society initiative, and before that, the Digital Agenda, which has provided a favorable market environment for the deployment of ultra-broadband and Gigabit network solutions. Although the overall environment and market demand for broadband service deployment in the European Union have improved, some new broadband technologies are still being reviewed for regulatory and standards compliance, which may affect the timing of those technologies. The competitive landscape in certain international markets is also ~~effected~~affected by the increased presence of Asian manufacturers that seek to compete aggressively on price. Our revenue and operating income in ~~our~~some international markets ~~can~~have been, and may continue to be, negatively impacted by a strengthening U.S. ~~dollar.~~dollar, adverse changes in trade policy and disruptions in international trade due to the COVID-19 pandemic. Consequently, while we expect the global trend towards deployment of more robust broadband speeds and access to continue creating additional market opportunities for us in the long-run, the factors described above may result in negative pressure on revenue and operating income.

As a percentage of sales, cost of sales decreased from ~~67.1% in~~57.8% for the three months ended March 31, ~~2018~~2019 to ~~57.8% in~~54.9% for the three months ended March 31, 2020. The decrease was primarily attributable to changes in customer and product mix, a regional revenue shift, changes in services and support mix and a decrease in fixed personnel costs as a result of a restructuring program initiated in 2019.

Network Solutions cost of sales, as a percentage of that segment’s sales, decreased from 56.2% for the three months ended March 31, 2019 to 53.0% for the three months ended March 31, 2020. The decrease in cost of sales as a percentage of sales for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to changes in customer and product mix, a regional revenue shift ~~customer and product mix, services and support mix~~ and a decrease in ~~labor expense~~fixed personnel costs as a result of a restructuring program initiated in ~~the first quarter of 2018.~~

~~Network Solutions cost of sales, as a percent of that segment’s sales, decreased from 65.2% in the three months ended March 31, 2018 to 56.2% in the three months ended March 31,~~ 2019. The decrease in cost of sales as a percentage of sales for the three months ended March 31, 2019 is primarily attributable to a regional revenue shift, customer and product mix and a decrease in labor expense due to a restructuring program in the first quarter of 2018.

An important part of our strategy is to reduce the cost of each succeeding generation of product ~~generation~~ and then lower the product’s selling price based on the cost savings achieved in order to gain market share and/or improve gross margins. This may cause variations in our gross profit percentage due to timing differences between the recognition of cost reductions and the lowering of product selling prices.

Services & Support cost of sales, as a ~~percent~~percentage of that segment’s sales, decreased from ~~80.1% in~~69.3% for the three months ended March 31, ~~2018~~2019 to ~~69.3% in~~65.9% for the three months ended March 31, ~~2019.~~2020. The decrease in cost of sales as a percentage of sales for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to ~~lower~~customer mix, changes in services and support mix and a decrease in fixed personnel costs ~~due to~~as a result of a restructuring program initiated in ~~the first quarter of 2081, customer mix and services and support mix.~~2019.

~~Our~~ Services & Support revenue is comprised of network planning and implementation, maintenance, support and cloud-based management services, with network planning and implementation being the largest and fastest growing component in the long-term. Compared to our other services, such as maintenance, support and cloud-based management services, our network planning and implementation services typically utilize a higher percentage of internal and subcontracted engineers, professionals and contractors to perform the work for customers. The additional costs incurred to perform these infrastructure and labor-intensive services inherently result in lower average gross margins as compared to maintenance and support services.

As our network planning and implementation revenue grew ~~and is now~~to become the largest component of our Services & Support segment business, our Services & Support segment gross margins decreased versus those reported when maintenance and support comprised the majority of the business. Further, because the growth in our network planning and implementation services has resulted in our Services & Support segment revenue comprising a larger percentage of our overall revenue, and because our Services & Support segment gross margins are generally below those of the Network Solutions segment, our overall corporate gross margins have declined as that business has continued to grow. Within the Services & Support segment, we do expect variability in gross margins from quarter-to-quarter based on the mix of the services recognized.

Selling, general and administrative expenses increased 4.8% from $33.5 million in the three months ended March 31, 2018 to $35.1 million in the three months ended March 31, 2019. The increase in selling, general and administrative expenses for the three months ended March 31, 2019 is primarily attributable to increases in deferred compensation expense and incremental expenses as a result of the SmartRG acquisition.

As a percentage of sales, selling, general and administrative expenses decreased from ~~27.8% in~~24.4% for the three months ended March 31, ~~2018~~2019 to ~~24.4% in~~23.2% for the three months ended March 31, ~~2019.~~2020. Selling, general and administrative expenses as a percentage of sales ~~may~~will generally fluctuate whenever there is a significant fluctuation in revenue for the periods being compared.

~~Research~~Selling, general and ~~development~~administrative expenses decreased ~~3.7%~~24.2% from ~~$32.8~~$35.1 million infor the three months ended March 31, ~~2018~~2019 to ~~$31.6~~$26.6 million infor the three months ended March 31, ~~2019.~~2020. The decrease in ~~research~~selling, general and ~~development~~administrative expenses for the three months ended March 31, ~~2019 is~~2020 was primarily attributable to ~~decreases in restructuring~~lower deferred compensation related costs and labor ~~expenses,~~expense partially due to the restructuring program initiated in 2019, partially offset by increases in costs for contract services related to an ~~increase in incremental expenses as a result of the SmartRG and Sumitomo acquisitions.~~enterprise resource planning implementation project.

As a percentage of sales, research and development expenses ~~decreased~~increased from ~~27.2% in~~22.0% for the three months ended March 31, ~~2018~~2019 to ~~22.0% in~~26.1% for the three months ended March 31, ~~2019.~~2020. Research and development expenses as a percentage of sales will fluctuate whenever there are incremental product development activities or significant fluctuations in revenue for the periods being compared.

Research and development expenses decreased 5.6% from $31.6 million for the three months ended March 31, 2019 to $29.9 million for the three months ended March 31, 2020. The decrease in research and development expenses for the three months ended March 31, 2020 was primarily attributable to lower labor expense and other expenses which were mainly as result of a restructuring program initiated in 2019.

We expect to continue to incur research and development expenses in connection with our new and existing products and our continued expansion into international markets. We continually evaluate new product opportunities and engage in ~~intensive~~significant research and product development efforts, which provides for new product development, enhancement of existing products and product cost reductions. We may incur significant research and development expenses prior to the receipt of revenue from a major new product group.

Asset impairments, which were $0.1 million for the three months ended March 31, 2020, relate to the abandonment of certain information technology projects in which we had previously capitalized costs. There were no asset impairments recognized during the three months ended March 31, 2019.

Interest and dividend income decreased ~~31.8%~~39.8% from ~~$0.9 million in the three months ended March 31, 2018 to~~ $0.6 million ~~in the three months ended March 31, 2019. The decrease in interest and dividend income~~ for the three months ended March 31, 2019 isto $0.4 million for the three months ended March 31, 2020. The decrease in interest and dividend income was primarily attributable to ~~fluctuations~~a decrease in interest income as a result of a decline in our investment ~~balances.~~balances primarily due to the maturity of our certificate of deposit which served as collateral for our taxable revenue bonds. Our total investments decreased from $116.5 million as of March 31, 2019 to $85.1 million as of March 31, 2020.

Interest expense, which is primarily related to our taxable revenue ~~bond, remained constant at~~bonds, decreased by $0.1 million ~~for both~~in the three months ended March 31, ~~2018 and 2019, as we had no substantial change~~2020 compared to the three months ended March 31, 2019. The decrease was due to the fact that the outstanding principal balance of the taxable revenue bonds was paid off upon maturity in ~~our fixed-rate borrowing.~~January 2020. See “Liquidity and Capital Resources” below for additional information on our revenue bond.

We recognized a net investment gain ~~(loss) increased from a loss~~ of ~~$(0.1)~~$5.9 million infor the three months ended March 31, ~~2018 to~~2019 and a ~~gain~~net investment loss of ~~$5.9~~$10.9 million infor the three months ended March 31, ~~2019.~~2020. The ~~fluctuation~~fluctuations in our net ~~investment gain (loss) is~~investments were primarily attributable to changes in the fair value ~~on equity~~of our securities recognized during the period. For the three months ended March 31, 2020, our investments were negatively impacted by the market conditions due to the COVID-19 pandemic, which resulted in a sharp downturn in the markets during the quarter. We expect that any future market volatility, whether from COVID-19 or other factors, will result in continued volatility in our investment portfolio. See Note 76 of the Notes to Condensed Consolidated Financial Statements, included in Part I, Item 1 of this report, and “Investing Activities” in “Liquidity and Capital Resources” below for additional information.

Other income, ~~(expense), net, is comprised primarily of miscellaneous income, gains and losses on foreign currency transactions and gains and losses on foreign exchange forward contracts. Other income (expense),~~ net increased from ~~$0.1 million~~income of ~~expense in the three months ended March 31, 2018 to~~ $0.9 million ~~of income in the three months ended March 31, 2019. The change in other income (expense), net~~ for the three months ended March 31, 2019 ~~is primarily attributable~~ to income of $1.1 million for the three months ended March 31, 2020. For the three months ended March 31, 2020, other income, net consisted mainly of gains and losses on foreign currency transactions. For the three months ended March 31, 2019, other income, net consisted mainly of the receipt of insurance proceeds from a life insurance policy.

~~Gain on bargain purchase~~Our effective tax rate decreased from an expense of ~~a business was $11.3 million during~~28.6% for the three months ended March 31, ~~2018 and is related~~2019 to ~~our acquisition~~a benefit of ~~Sumitomo Electric Lightwave Corp.’s North American EPON business and entry into a technology license and supply agreement with Sumitomo Electric Industries, Ltd. in March 2018. No gain on bargain purchase of a business was recorded during~~30.5% for the three months ended March 31, ~~2019.~~2020. The decrease in the effective tax rate was primarily driven by the impact recorded from the Coronavirus Aid, Relief, and Economic Security (the “CARES Act”) Act signed into law on March 27, 2020, partially offset by tax expense in our international operations and changes in our valuation allowance related to our domestic operations. See Note 23 of the Notes to Condensed Consolidated Financial Statements included in Part I, Item 1 of this report for additional information.

Our effective tax rate increased from a benefit of 15.1%, excluding the tax effect of the bargain purchase gain, in the three months ended March 31, 2018 to an expense of 28.6% three months ended March 31, 2019. The increase in the effective tax rate between the two periods is primarily driven by the shift to profitability in the current quarter.

As a result of the above factors, net income ~~increased $11.6~~(loss) decreased from net income of $0.8 million ~~from a net loss of $10.8 million in~~for the three months ended March 31, ~~2018~~2019 to a net ~~income~~loss of ~~$0.8~~$10.0 million infor the three months ended March 31, ~~2019.~~2020.

We ~~intend~~have historically financed, and we currently expect to continue to finance, our ~~operations~~ongoing business with existing cash, investments and cash flow from operations. We have used, and expect to continue to use, ~~the~~existing cash, investments and cash generated from operations for working capital, business acquisitions, purchases of treasury stock, shareholder dividends ~~business acquisitions~~ and other general corporate purposes, including ~~(i)~~ product development activities to enhance our existing products and develop new products, ~~and (ii)~~ expansion of our sales and marketing ~~activities.~~activities and capital expenditures. We believe our cash and cash equivalents, investments and cash generated from operations to be adequate to meet our operating and capital needs for at least the next 12 months.

AtAs of March 31, ~~2019,~~2020, cash on hand was ~~$109.1~~$71.3 million and short-term investments were ~~$31.3~~$6.0 million, which resulted in available short-term liquidity of ~~$140.4~~$77.3 million, of which ~~$70.2~~$47.5 million was held by our foreign subsidiaries. AtAs of December 31, ~~2018,~~2019, cash on hand was ~~$105.5~~$73.8 million and short-term investments were ~~$3.2~~$33.2 million, which resulted in available short-term liquidity of ~~$108.7~~$107.0 million, of which ~~$87.1~~$52.3 million was held by our foreign subsidiaries. The ~~increase~~decrease in short-term liquidity from December 31, ~~2018~~2019 to March 31, ~~2019~~2020 is primarily attributable to the ~~restricted~~maturity of a certificate of deposit ~~totaling~~of $25.6 million ~~being reclassified from a long-term investment to a short-term investment.~~that served as collateral for our revenue bond, which matured in January 2020.

Our working capital, ~~which consists of~~defined as current assets less current liabilities, decreased ~~0.8%~~1.6% from ~~$237.4~~$207.6 million as of December 31, ~~2018~~2019 to ~~$235.4~~$204.4 million as of March 31, ~~2019,~~2020, and our current ratio, defined as current assets divided by current liabilities, ~~decreased~~increased from ~~3.01~~2.84 as of December 31, ~~2018~~2019 to ~~2.66~~3.29 as of March 31, ~~2019.~~2020. The ~~decreases~~decrease in our working capital and increase in our current ratio ~~are~~were primarily attributable to decreases in accounts receivable, and short-term investments, which consisted of a certificate of deposit related to our taxable revenue bond and the ~~reclassification of our bond~~related bonds payable, ~~to current liabilities as it matures~~partially offset by increases in ~~January 2020 as well as a decrease in inventory.~~other receivables and accounts payable. The quick ratio, defined as cash, cash equivalents, short-term investments, and net accounts receivable, divided by current liabilities, ~~decreased~~increased from ~~1.76~~1.75 as of December 31, ~~2018~~2019 to ~~1.69~~1.83 as of March 31, ~~2019.~~2020. The ~~decrease~~increase in the quick ratio iswas primarily attributable to the ~~reclassification~~payment of our bond payable ~~to current liabilities as it matures~~upon maturity in January 2020, partially offset by ~~an increase~~a decrease in accounts receivable and cash and cash equivalents ~~and short-term investments, mainly related to the reclassification of our restricted certificate of deposit from a long-term investment to a short-term investment.~~along with an increase in accounts payable.

Net accounts receivable decreased ~~0.4%~~4.5% from ~~$99.4~~$90.5 million atas of December 31, ~~2018~~2019 to ~~$99.0~~$86.5 million atas of March 31, ~~2019.~~2020. Our allowance for doubtful accounts was ~~$0.1 million at December 31, 2018 and March 31, 2019. Quarterly accounts receivable day’s sales outstanding (DSO) decreased from 65 days~~$38 thousand as of December 31, ~~2018 to 62 days as of~~2019 and March 31, ~~2019.~~2020. The decrease in net accounts receivable iswas due to a decrease in sales volume. Quarterly accounts receivable DSO decreased from 72 days as of December 31, 2019 to 69 days as of March 31, 2020. The decrease in DSO was due to the timing of ~~international~~product shipments and customer mix.

Other receivables ~~decreased 5.8%~~increased 39.6% from ~~$36.7~~$16.6 million atas of December 31, ~~2018~~2019 to ~~$34.6~~$23.1 million atas of March 31, ~~2019.~~2020. The ~~decrease~~increase in other receivables iswas primarily attributable to an increase in income tax receivables related to the CARES Act partially offset by a decrease in contract ~~assets, leased equipment receivables and income tax receivables partially offset by an increase in contract manufacturers’ receivables.~~assets.

Quarterly inventory turnover ~~increased~~decreased from ~~3.29~~2.70 turns as of December 31, ~~2018~~2019 to ~~3.44~~2.54 turns atas of March 31, ~~2019.~~2020. Inventory ~~decreased 6.2%~~increased 1.2% from ~~$99.8~~$98.3 million atas of December 31, ~~2018~~2019 to ~~$93.6~~$99.5 million atas of March 31, ~~2019. We~~2020. Barring COVID-19 uncertainties related to supply chain and demand, we expect inventory levels to fluctuate as we attempt to maintain sufficient inventory in response to ~~services activity and~~ seasonal cycles of our business and ensuring competitive lead times while managing the risk of ~~inventory obsolescence that may occur due to rapidly changing technology and customer demand.~~inventory.

Accounts payable ~~remained consistent at $60.1~~increased 6.3% from $44.9 million atas of December 31, ~~2018 and~~2019 to $47.7 million as of March 31, ~~2019.~~2020. Accounts payable will fluctuate due to variations in the timing of the receipt of supplies, inventory and services and our subsequent payments for these purchases.

Capital expenditures totaled approximately ~~$1.9~~$1.4 million and ~~$2.0~~$1.9 million for the three months ended March 31, ~~2019~~2020 and ~~2018,~~2019, respectively. These expenditures were primarily used to purchase ~~computer hardware, software,~~ manufacturing and test equipment, software, computer hardware and to finance building improvements.

Our combined short-term and long-term investments ~~increased $4.4~~decreased $42.6 million from ~~$112.1~~$127.7 million atas of December 31, ~~2018~~2019 to ~~$116.5~~$85.1 million atas of March 31, ~~2019.~~2020. This ~~increase~~decrease reflects the maturity of a certificate deposit which served as collateral for our revenue bond and the impact of net realized and unrealized gains and losses on our ~~combined investments plus new investments, partially offset by cash used for share repurchases, shareholder dividends and property, plant and equipment purchases.~~investments.

We typically invest all available cash not required for immediate use in operations, primarily in securities that we believe bear minimal risk of loss. ~~At March 31, 2019, these investments~~See Note 6 of the Notes to Condensed Consolidated Financial Statements included ~~corporate bonds~~in Part I, Item 1 of $16.0 million, municipal bonds of $0.9 million, asset-backed bonds of $7.2 million, mortgage/agency bonds of $4.5 million, U.S. government bonds of $4.2 million and foreign government bonds of $2.2 million. At December 31, 2018, these investments included corporate bonds of $20.7 million, municipal fixed-rate bonds of $1.3 million, asset-backed bonds of $5.2 million, mortgage/agency-backed bonds of $3.8 million, U.S. government bonds of $9.2 million and foreign government bonds of $0.6 million.this report for additional information. As of March 31, ~~2019, our corporate bonds, municipal fixed-rate bonds, asset-backed bonds, mortgage/agency-backed bonds, U.S. government bonds and foreign government bonds~~2020, investments were classified as available-for-sale and had a combined duration of ~~0.96~~1.64 years with an average Standard & Poor’s credit rating of ~~A+.~~AA. Because our ~~bond~~investment portfolio has a high-quality rating and contractual maturities of short duration, we are able to obtain prices for these bonds derived from observable market inputs, or for similar securities traded in an active market, on a daily basis.

Our long-term investments decreased ~~21.7%~~16.2% from ~~$108.8~~$94.5 million atas of December 31, ~~2018~~2019 to ~~$85.2~~$79.1 million at March 31, 2019. Long-term investments at December 31, 2018 included an investment in a certificate of deposit of $25.6 million, which serves as collateral for our revenue bond. This certificate of deposit is now included in short-term investments as of March 31, ~~2019, as this bond matures on January 1,~~ 2020. ~~See “Debt” below for additional information. We also have~~Our investments ininclude various marketable equity securities classified as long-term investments with a fair market value of ~~$30.9~~$24.8 million and ~~$27.0~~$35.8 million, atas of March 31, ~~2019~~2020 and December 31, ~~2018,~~2019, respectively. Long-term investments atas of March 31, ~~2019~~2020 and December 31, ~~2018~~2019 also included ~~$20.4~~$17.1 million and ~~$18.3~~$21.7 million, respectively, related to our deferred compensation ~~plans.~~

~~Acquisition of businesses, net of cash acquired, totaled $7.8~~plans, and $0.3 million for ~~the three months ended March 31, 2018. No businesses were acquired during the three months ended March 31, 2019. See Note 2~~both years, of ~~Notes to Consolidated Financial Statements included~~other investments, consisting of interests in ~~Item 1 of this report for additional information.~~two private equity funds.

In July 2003, our Board of Directors elected to begin declaring quarterly dividends on our common stock considering the tax treatment of dividends and adequate levels of Company liquidity. During the three months ended March 31, ~~2019~~2020 and ~~2018,~~2019, we paid dividends totaling $4.3 ~~million~~million. The continued payment of dividends is at the discretion of the Company’s Board of Directors and ~~$4.4 million, respectively.~~is subject to general business conditions and ongoing financial results of the Company.

~~We have amounts outstanding under loans made pursuant to~~In conjunction with the 1995 expansion of our Huntsville, Alabama, facility, we were approved for participation in an incentive program offered by the State of Alabama ~~State~~ Industrial Development Authority (the “Authority”). Pursuant to the program, in January 1995, the Authority issued $20.0 million of its taxable revenue ~~bond (the Bond) which totaled $25.6 million at March 31, 2019~~bonds and ~~December 31, 2018. At March 31, 2019,~~loaned the ~~estimated fair value~~proceeds from the sale of these taxable revenue bonds to the ~~Bond was $25.5 million, based~~Company. Further advances on ~~a debt security with a comparable interest rate and maturity and a Standard & Poor’s credit rating of AAA. Restricted funds serving as a collateral deposit against~~ the ~~principal~~taxable revenue bonds were made by the Authority, bringing the total amount ~~of the Bond in the amount of $25.6 million were included in short-term and long-term investments at March 31, 2019, and December 31, 2018, respectively. We have the right~~outstanding to ~~set-off the balance of the Bond with the collateral deposit in order to reduce the balance of the indebtedness.~~$50.0 million. The ~~Bond matures~~bonds matured on January 1, 2020, and bears interest at the rate of 2% per annum. In conjunction with this program, we are eligible to receive certain economic incentives from the state of Alabama that reduce the amount of payroll withholdings we are required to remit to the state for those employment positions that qualify under this program. We are required to make payments in the amounts necessary to pay the interest on the amounts currently outstanding. It is our intent to make annual principal payments in addition to the interest amounts that are due. The restricted funds held as collateral against the principal amount of the Bond will be used to pay the outstanding ~~principal and interest upon the Bond’s maturity~~balance of $24.6 million was repaid in full on January 1,2, 2020.

Since 1997, our Board of Directors has approved multiple share repurchase programs that have authorized ~~open market repurchase transactions~~repurchases of our common stock, which are implemented through open market or private purchases from time to time as conditions warrant. We currently have authorization to repurchase an additional 2.5 million shares of our common stock under the current authorization of up to 5.0 million shares. During the three months ended March 31, 2020, there were no common stock repurchases. During the three months ended March 31, 2019, we repurchased 13,000 shares of our common stock for $0.2 million at an average price of $14.06 per share. ~~We currently have authorization to repurchase an additional 2.5 million shares of our common stock under the current authorization of up to 5.0 million shares.~~

~~There were no stock options exercised during the three months ended March 31, 2019.~~

We do not have off-balance sheet financing arrangements and have not engaged in any related party transactions or arrangements with unconsolidated entities or other persons that are reasonably likely to materially affect liquidity or the availability of or requirements for capital resources. During the three months ended March 31, ~~2019,~~2020, there have been no material changes in contractual obligations and commercial commitments from those discussed in ~~our most recent Annual Report on~~the 2019 Form ~~10-K for the year ended December 31, 2018 filed on February 28, 2019 with the SEC.~~10-K.

We have committed to invest up to an aggregate of $7.9 million in two private equity funds, ~~and we have contributed $8.4 million as of March 31, 2019,~~ of which $7.7 million has been applied ~~to these commitments.~~as of March 31, 2020.

We are exposed to financial market risks, including changes in ~~interest rates,~~ foreign currency rates, ~~and~~ prices of marketable equity and fixed-income securities. The primary objective of the large majority of our investment activities is to preserve principal while at the same time achieving appropriate yields without significantly increasing risk. To achieve this objective, a majority of our marketable securities are investment grade, ~~corporate bonds, municipal~~ fixed-rate ~~bonds, asset-backed bonds, mortgage/agency-backed bonds, U.S. and foreign government~~ bonds and municipal money market instruments denominated in U.S. dollars. Our investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5% of the market value of our total investment portfolio.

We maintain depository investments with certain financial institutions. Although these depository investments may exceed government insured depository limits, we have evaluated the credit-worthiness of these financial institutions, and determined the risk of material financial loss due to exposure of such credit risk to be minimal. As of March 31, ~~2019, $106.2~~2020, $68.8 million of our cash and cash equivalents, primarily certain domestic money market funds and foreign depository accounts, were in excess of government provided insured depository limits.

As of March 31, ~~2019,~~2020, approximately ~~$37.1~~$43.0 million of our cash and investments may be directly affected by changes in interest rates. ~~We have performed a hypothetical sensitivity analysis assuming market interest rates increase or decrease by 50 basis points (bps) for an entire year, while all other variables remain constant. At~~As of March 31, ~~2019,~~2020, we held ~~$10.1~~$7.6 million of cash and variable-rate investments where a change in interest rates would impact our interest income. A hypothetical 50 ~~bps~~basis points decline in interest rates as of March 31, ~~2019~~2020, assuming all other variables remain constant, would reduce annualized interest income on our cash and investments by approximately $0.1 million. In addition, we held ~~$26.9~~$35.3 million of fixed-rate bonds whose fair values may be directly affected by a change in interest rates. A hypothetical 50 bps increase in interest rates as of March 31, ~~2019~~2020, assuming all other variables remain constant, would reduce the fair value of our fixed-rate bonds by approximately ~~$0.1~~$0.3 million.

We are exposed to changes in foreign currency exchange rates to the extent that such changes affect our revenue and gross margin on revenue derived from some international customers, expenses, and assets and liabilities held in non-functional currencies related to our foreign subsidiaries. Our primary exposures to foreign currency exchange ~~rates~~rate movements are with our German subsidiary, whose functional currency is the Euro, and our Australian subsidiary, whose functional currency is the Australian ~~dollar, and our Mexican subsidiary, whose~~dollar. Our revenue is primarily denominated in the respective functional currency of the subsidiary and paid in that subsidiary’s functional currency or certain other local currency, our global supply chain predominately invoices us in the respective functional currency of the subsidiary and is paid in U.S. dollars and some of our operating expenses are invoiced and paid in certain local currencies (approximately 11% of total operating expense for the ~~U.S. dollar. We~~three months ended March 31, 2020). Therefore, our revenues, gross margins, operating expense and operating income are ~~exposed~~all subject to ~~changes in~~ foreign currency exchange rates to the extent of our German subsidiary’s use of contract manufacturers and raw material suppliers whom we predominately pay in U.S. dollars. We may establish cash flow hedges utilizing foreign exchange forward contracts to reduce the risk that movements in exchange rates will adversely affect the net cash flows resulting from the planned purchase of products from foreign suppliers.fluctuations. As a result, changes in currency exchange rates could cause variations in ~~gross margin in the products that we sell in the EMEA region.~~our operating income.

We have certain customers and suppliers who are invoiced or pay in a non-functional currency. Changes in the monetary exchange rates used to invoice such customers versus the functional currency of the entity billing such customers may adversely affect our results of operations and financial ~~condition, as outstanding non-functional balances are revalued to the functional currency through profit and loss. When appropriate, we utilize foreign exchange forward contracts to help~~condition. To manage the volatility relating to these ~~valuation exposures. All changes in the fair value of our~~typical business exposures, we may enter into various derivative ~~instruments that do not qualify for or are not designated for hedged accounting~~ transactions, ~~are recognized as other income (expense), net in the Consolidated Statements of Income.~~when appropriate. We do not hold or issue derivative instruments for trading or other speculative purposes. All non-functional currencies billed would result in a combined hypothetical gain or loss of ~~$1.1~~$1.0 million if the U.S. dollar weakened or strengthened 10% against the billing currencies. ~~The fluctuation~~This change represents a decrease in the amount of hypothetical gain or loss compared to prior periods and is mainly due to ~~an increase~~a decrease in U.S. dollar-denominated billings in a non-U.S. dollar denominated ~~subsidiary as well as an increase in international sales.~~subsidiary. Although we do not currently hold any derivative instruments, any gain or loss would be partially mitigated by ~~these~~any derivative ~~instruments.~~instruments held.

As of March 31, ~~2019,~~2020, we ~~have~~had certain material contracts subject to currency revaluation, including accounts receivable, accounts payable and lease liabilities, denominated in foreign currencies. As of March 31, ~~2019,~~2020, we did not have any forward contracts outstanding.

For further information about the fair value of our investments ~~and our derivative and hedging activities~~ as of March 31, ~~2019,~~2020, see ~~Notes 7 and 8~~Note 6 of the Notes to Condensed Consolidated Financial Statements included in Part I, Item 1 of this report.

We maintain disclosure controls and ~~procedures.~~ ~~Our Chief Executive Officer and Chief Financial Officer~~procedures that are ~~responsible for establishing and maintaining "disclosure controls and procedures" (as defined~~designed to provide reasonable assurance that the information required to be disclosed by us in reports that we file or submit under the Securities Exchange Act of 1934, ~~Rules 13a-15(e)~~as amended (the “Exchange Act”), is recorded, processed, summarized and ~~15d-15(e)) for ADTRAN. Our~~reported within the time periods specified in the rules and forms promulgated by the SEC, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and our Chief Financial Officer, ~~after evaluating~~as appropriate, to allow timely decisions regarding required disclosure. Because of the inherent limitations to the effectiveness of ~~our~~any system of disclosure controls and procedures, asno evaluation of disclosure controls and procedures can provide absolute assurance that all control issues, if any, with a company have been prevented or detected on a timely basis. Even disclosure controls and procedures determined to be effective can only provide reasonable assurance that their objectives are achieved.

As of the end of the period covered by this ~~quarterly~~ report, ~~have~~an evaluation was carried out by management, including our Chief Executive Officer and our Chief Financial Officer, of the effectiveness of our disclosure controls and procedures (as defined in Exchange Act Rule 13a-15(e)) pursuant to Rule 13a-15 of the Exchange Act. Based on that evaluation, our Chief Executive Officer and our Chief Financial Officer concluded that our disclosure controls and procedures ~~are effective.~~were not effective as of March 31, 2020 due to the material weakness in our internal control over financial reporting described below.

A material weakness is a significant deficiency, or combination of significant deficiencies, in internal control over financial ~~reporting.~~ ~~There~~reporting, such that there is a reasonable possibility that a material misstatement of the Company’s annual or interim financial statements will not be prevented or detected on a timely basis. In its assessment of the effectiveness of internal control over financial reporting as of March 31, 2020, management determined that there was a deficiency in ADTRAN’s internal control over financial reporting that constituted a material weakness. Specifically, management determined that the Company did not design and maintain effective internal control over the valuation of inventory:

Despite the existence of this material weakness, we believe that the consolidated financial statements included in this report present fairly, in all material respects, our financial position, results of operations and cash flows for the periods presented, in conformity with generally accepted accounting principles in the United States of America. This material weakness did not result in any material misstatements of the Company’s financial statements or disclosures for any period presented in the accompanying consolidated financial statements. While the above material weakness did not result in a material misstatement of the Company’s consolidated financial statements, the material weakness could result in a misstatement of the Company’s interim or annual consolidated financial statements and disclosures that would result in a material misstatement that would not be prevented or detected.

The Company has been working to redesign and implement enhanced controls and procedures related to the review of significant inputs and assumptions used to determine our excess and obsolete inventory reserve, and to ensure the completeness and accuracy of key reports and related data used in the calculation of the excess and obsolete inventory reserve. Key reports and calculations have been redesigned and fully integrated into our enterprise resource planning system to ensure completeness and the accuracy of significant inputs. New controls and procedures have also been established by the Company around the consideration of historical usage, known trends, market conditions, and estimated net realizable value of the inventory. The implementation of these measures is ongoing, and, while we believe that they will be effective in remediating the material weakness, management has concluded that, as of March 31, 2020, our controls related to our excess and obsolete inventory reserve were not effectively designed and maintained, and the material weakness related to these controls continued to exist.

Except as noted in the preceding paragraphs, there were no changes in our internal control over financial reporting that occurred during ~~our most recent~~the fiscal quarter ended March 31, 2020 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

On October 17, 2019, a purported stockholder class action lawsuit, captioned Burbridge v. ADTRAN, Inc. et al., Docket No. 19-cv-09619, was filed in the United States District Court for the Southern District of New York against the Company, two of its current executive officers and one of its former executive officers. The complaint alleges violations of federal securities laws and seeks unspecified compensatory damages on behalf of purported purchasers of ADTRAN securities between February 28, 2019 and October 9, 2019. The lawsuit claims that the defendants made materially false and misleading statements regarding, and/or failed to disclose material adverse facts about, the Company’s business, operations and prospects, specifically relating to the Company’s internal control over financial reporting, excess and obsolete inventory reserves, financial results and demand from certain customers. The lawsuit was transferred to the U.S. District Court for the Northern District of Alabama on January 7, 2020, and co-lead plaintiffs have been appointed to represent the putative class. The plaintiffs filed an amended complaint on April 30, 2020. The defendants intend to file a motion to dismiss the amended complaint. We deny the allegations in the complaint, as amended, and intend to vigorously defend against this lawsuit. At this time, we are unable to predict the outcome of or estimate the possible loss or range of loss, if any, associated with this lawsuit.

On March 31, 2020, a shareholder derivative suit, captioned Johnson (Derivatively on behalf of ADTRAN) v. T. Stanton, M. Foliano, R. Shannon, and Board of Directors, case no. 5:20-cv-00447, was filed in the U.S. District Court of Northern Alabama against two of the Company’s current executive officers, one of its former executive officers and its Board of Directors. The derivative suit, which is purportedly brought on behalf of ADTRAN, makes similar allegations as the shareholder class action and accuses the directors and officers of breaches of fiduciary duty in connection with those allegations. The Company expects that the derivative lawsuit will be stayed by the Court pending resolution of the class action. The Company and its defendants disagree with the claims made in the complaint, and the defendants intend to vigorously defend against this lawsuit. At this time, we are unable to predict the outcome of or estimate the possible loss or range of loss, if any, associated with this lawsuit.

A list of factors that could materially affect our business, financial condition or operating results is described in Part I, Item 1A, “Risk Factors” in ~~our Annual Report on~~the 2019 Form ~~10-K for the year ended December 31, 2018.~~10-K. There have been no material changes to our risk factors ~~since our Annual Report on~~from those disclosed in Part I, Item 1A, “Risk Factors” in the 2019 Form 10-K, other than as described in the risk factor below.

The ongoing COVID-19 pandemic could adversely affect our business, results of operations and financial condition.

In March 2020, the World Health Organization declared the outbreak of COVID-19 a pandemic. COVID-19 continues to spread throughout the U.S. and the world and has resulted in authorities implementing numerous measures to contain the virus, including travel bans and restrictions, quarantines, shelter-in-place orders, and business limitations and shutdowns. While we are unable to accurately predict the full impact that COVID-19 will have on our results from operations, financial condition, liquidity and cash flows due to numerous uncertainties, including the duration and severity of the pandemic and containment measures, our compliance with these measures has impacted, and may continue to impact, our day-to-day operations and could continue to disrupt our business and operations, as well as that of our customers, suppliers (including contract manufacturers) and other counterparties, for an indefinite period of time. We have experienced, and may continue to experience, disruptions in our supply chain, including a slow-down in supply chain deliveries and some raw material and freight-related cost, increases as a result of the ~~year ended December 31, 2018.~~pandemic.

To support the health and well-being of our employees, customers, partners and communities, a vast majority of our employees are working remotely as of May 8, 2020. In addition, many of our customers, suppliers and other counterparties are working remotely, which may delay the timing of some orders and expected deliveries. The disruptions to our operations caused by COVID-19 may result in inefficiencies, delays and additional costs in our product development, sales, marketing and customer service efforts that we cannot fully mitigate through remote or other alternative work arrangements.

More generally, the pandemic raises the possibility of an extended global economic downturn and has caused volatility in financial markets, which could affect demand for our products and services and impact our results and financial condition even after the pandemic is contained and the shelter-in-place orders are lifted. For example, we may be unable to collect receivables from those customers significantly impacted by COVID-19. Also, a decrease in orders could negatively affect our revenues in future periods, particularly if experienced on a sustained basis.

Although we expect that current cash and cash equivalent balances and cash flows that are generated from operations will be sufficient to meet our domestic and international working capital needs and other capital and liquidity requirements for at least the next 12

months, if our access to capital is restricted or our borrowing costs increase as a result of the COVID-19 pandemic, our operations and financial condition could be adversely impacted.

Moreover, the impacts of the COVID-19 pandemic may exacerbate other pre-existing risks, such as political, regulatory, social, financial, operational and cybersecurity risks, and those associated with global economic conditions, any of which could have a material adverse effect on our business.

We will continue to evaluate the nature and extent of the impact of COVID-19 on our business.

The following table sets forth repurchases of our common stock for the months indicated:

Period

Total
Number of
Shares
Purchased

Average
Price
Paid per
Share

Total Number of
Shares Purchased
as Part of Publicly
Announced Plans
or Programs

Maximum Number
of Shares that May
Yet Be Purchased
Under the Plans or
Programs

January 1, 2019 – January 31, 2019

—

$
—

—

2,558,516

February 1, 2019 – February 28, 2019

13,086

$
14.06

13,086

2,545,430

March 1, 2019 – March 31, 2019

—

$
—

—

2,545,430

Total

13,086

13,086

Period	Total Number of Shares Purchased		Average Price Paid per Share		Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs⁽¹⁾		Maximum Number of Shares that May Yet Be Purchased Under the Plans or Programs
January 1, 2020 – January 31, 2020		—	$	—		—		2,545,430
February 1, 2020 – February 29, 2020		—	$	—		—		2,545,430
March 1, 2020 – March 31, 2020		—	$	—		—		2,545,430
Total		—				—

On July 14, 2015, our Board of Directors authorized the repurchase of an additional 5.0 million shares of our common stock (bringing the total shares authorized for repurchase to 50.0 million). This authorization will be implemented through open market or private purchases from time to time as conditions warrant.

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Delaware	63-0918200
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)
901 Explorer Boulevard Huntsville, Alabama	35806-2807
(Address of principal executive offices)	(Zip Code)


Acronym/Concept/ Defined Term	Meaning
carrier	Entity that provides voice, data or video services to consumers and businesses
CLEC	Competitive Local Exchange Carrier
CPE	Customer-Premises Equipment
CSP	Communication Service Provider
DSO	Days Sales Outstanding
FCC	Federal Communications Commission
FTTN	Fiber to the Node
Gfast	A digital subscriber line protocol standard for local loops (telephone lines) shorter than 500 meters with performance targets between 100 Mbps (as defined below) and 1 gigabit per second, depending on loop length
LAN	Local Area Network
MSO	Multiple System Operator
PON	Passive Optical Network
RSP	Regional Service Provider
SD-Access	Software Defined Access
Service Provider	An entity that provides voice, data or video services to consumers and businesses
System Integrator	Person or company that specializes in bringing together component subsystems into a whole and ensuring that those subsystems function together
U.S.	United States
VDSL2	Very high-speed Digital Subscriber Line 2
WAN	Wide Area Network

(In thousands)	SmartRG			Sumitomo
Assets
Tangible assets acquired	$	8,594		$	1,006
Intangible assets		9,960			22,100
Goodwill		3,489			—
Total assets acquired		22,043			23,106
Liabilities
Liabilities assumed		(6,001	)		(3,978	)
Total liabilities assumed		(6,001	)		(3,978	)
Total net assets		16,042			19,128
Gain on bargain purchase of a business, net of tax		—			(11,322	)
Total purchase price	$	16,042		$	7,806

(In thousands)	For the Three Months Ended March 31, 2018
Pro forma revenue	$	129,584
Pro forma net loss	$	(23,400	)
Pro forma loss per share - basic	$	(0.49	)
Pro forma loss per share - diluted	$	(0.49	)

	March 31, 2020
(In thousands)	Deferred Tax Assets		Valuation Allowance			Deferred Tax Assets, net
Domestic	$	52,355	$	(52,355	)	$	—
International		9,797		(2,350	)		7,447
Total	$	62,152	$	(54,705	)	$	7,447

	As of December 31, 2019
(In thousands)	Pre-Adoption		Effect of Adoption			As Presented Now
Condensed Consolidated Balance Sheet
Property, plant and equipment, net	$	73,708	$	(5,622	)	$	68,086
Other assets	$	14,261	$	5,622		$	19,883

	Three Months Ended			March 19 to
(In thousands)	March 31, 2019			March 31, 2018
Revenue	$	7,348		$	—
Net loss	$	(1,684	)	$	(77	)

(In thousands)	Value		Life (years)
Customer relationships	$	15,190	3 – 12
Developed technology		7,400	7
Licensed technology		5,900	9
Supplier relationship		2,800	2
Licensing agreements		560	5 – 10
Trade name		210	3
Total	$	32,060

	Number of Stock Options (in thousands)			Weighted Avg. Exercise Price (per share)		Weighted Avg. Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Stock options outstanding, December 31, 2018		4,382		$	22.91		4.10	$	—
Stock options granted		—		$	—
Stock options exercised		—		$	—
Stock options forfeited		(8	)	$	15.33
Stock options expired		(33	)	$	23.13
Stock options outstanding, March 31, 2019		4,341		$	22.93		3.80	$	—
Stock options exercisable, March 31, 2019		4,098		$	23.37		3.63	$	—

		Three Months Ended
	Income Statement	March 31,
(In thousands)	Location	2019		2018
Derivatives not designated as hedging instruments:
Foreign exchange contracts	Other income (expense), net	$	—	$	13

(In thousands)	Classification	March 31, 2020		December 31, 2019
Assets
Operating lease asset	Other assets	$	7,474	$	8,452
Total lease asset		$	7,474	$	8,452

Liabilities
Current operating lease liability	Accrued expenses	$	2,506	$	2,676
Non-current operating lease liability	Other non-current liabilities		5,012		5,818
Total lease liability		$	7,518	$	8,494

		March 31,		January 1,
(In thousands)	Classification	2019		2019
Assets
Operating lease asset	Other assets	$	9,502	$	10,322
Total lease assets		$	9,502	$	10,322

Liabilities
Current operating lease liability	Accrued expenses	$	2,718	$	2,948
Non-current operating lease liability	Other non-current liabilities		6,801		7,374
Total lease liability		$	9,519	$	10,322

(In thousands)	Classification	Three Months Ended March 31, 2019
Operating lease expense	Selling, general and administrative expenses	$	349
Operating lease expense	Research and development expenses		454
Operating lease expense	Cost of sales		16
Total lease expense		$	819

(In thousands)	Amount (1)
2019	$	3,873
2020		3,580
2021		2,771
2022		2,053
2023		1,317
Thereafter		762
Total	$	14,356

	As of March 31, ~~2019~~2020
Weighted average remaining lease term ~~(years)~~(in years)
Operating leases with USD functional currency		~~3.0~~2.2
Operating leases with Euro functional currency		~~5.1~~4.2
Weighted average discount rate
Operating leases with USD functional currency		~~4.61~~3.87	%
Operating leases with Euro functional currency		~~1.85~~1.83	%

~~(In thousands)~~	As of March 31, 2019
~~Cash paid for amounts included in the measurement of lease liabilities / assets~~
~~Cash used in operating activities related to operating leases~~		~~$ (811~~	)

~~Right-of-use assets obtained in exchange for lease obligations~~		~~$ 10,387~~

(In thousands)	Amount ⁽¹⁾
Remainder of 2019	$	9,005
2020		1,056
2021		493
2022		209
2023		78
Thereafter		2
Total	$	10,843

	Three Months Ended March 31, 2018
(In thousands)	Unrealized Gains (Losses) on Available- for-Sale Securities			Defined Benefit Plan Adjustments			Foreign Currency Adjustments			Total
Beginning balance	$	2,567		$	(4,286	)	$	(1,576	)	$	(3,295	)
Other comprehensive income (loss) before reclassifications		(257	)		—			842			585
Amounts reclassified from accumulated other comprehensive income (loss)		65			62			—			127
Amounts reclassified to retained earnings ⁽¹⁾		(3,220	)		—			—			(3,220	)
Net current period other comprehensive income (loss)		(3,412	)		62			842			(2,508	)
Ending balance	$	(845	)	$	(4,224	)	$	(734	)	$	(5,803	)

(In thousands)	March 31, 2020
Balance as of December 31, 2019	$	1,568
Plus: Amounts charged to cost and expense		553
Less: Amounts paid		(1,988	)
Balance as of March 31, 2020	$	133

(In thousands)	December 31, 2019
Balance as of December 31, 2018	$	185
Plus: Amounts charged to cost and expense		6,014
Less: Amounts paid		(4,631	)
Balance as of December 31, 2019	$	1,568

Exhibit No.		Description

31		Rule 13a-14(a)/15d-14(a) Certifications

32		Section 1350 Certifications

~~101.INS~~101		~~XBRL Instance Document-~~The following financial statements from the ~~instance document does not appear~~Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, formatted in Inline XBRL: (i) Condensed Consolidated Balance Sheets as of March 31, 2020 and December 31, 2019; (ii) Condensed Consolidated Statements of Income (Loss) for the ~~Interactive Data File because its XBRL tags are embedded within~~three months ended March 31, 2020 and 2019; (iii) Condensed Consolidated Statements of Comprehensive Income (Loss) for the ~~Inline XBRL document.~~three months ended March 31, 2020 and 2019; (iv) Condensed Consolidated Statements of Changes in Stockholders’ Equity for the three months ended March 31, 2020 and March 31, 2019; (v) Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2020 and 2019; and (vi) Notes to Consolidated Financial Statements

~~101.SCH~~104		Cover Page Interactive Data File (formatted as Inline XBRL ~~Taxonomy Extension Schema Document~~

~~101.CAL~~		~~XBRL Taxonomy Extension Calculation Linkbase Document~~

~~101.LAB~~		~~XBRL Taxonomy Extension Labels Linkbase Document~~

~~101.PRE~~		~~XBRL Taxonomy Extension Presentation Linkbase Document~~

~~101.DEF~~		~~XBRL Taxonomy Extension Definition Linkbase Document~~and contained in Exhibit 101)

		ADTRAN, Inc. (Registrant)


Date: May ~~7, 2019~~8, 2020		/s/ Michael Foliano
		Michael Foliano
		Senior Vice President of Finance and
		Chief Financial Officer (Duly Authorized Officer and Principal Financial Officer)
		~~(Principal Accounting Officer)~~

Large accelerated filer

Accelerated filer

Non-accelerated filer

~~Small~~Smaller reporting company

Emerging growth company