In connection with the Zetex acquisition, we adopted a contributory defined benefit plan that covers certain employees in the U.K. The defined benefit plan is closed to new entrants and frozen with respect to future benefit accruals. The retirement benefit is based on the final average compensation and service of each eligible employee. We determined the fair value of the defined benefit plan assets and utilize an annual measurement date of December 31. At subsequent measurement dates, defined benefit plan assets will be determined based on fair value. Defined benefit plan assets consist of a diverse range of listed and unlisted securities including corporate bonds and mutual funds and are denominated in the currency in which the benefits will be paid and that have terms to maturity approximating the terms of the related pension liability. The net pension and supplemental retirement benefit obligations and the related periodic costs are based on, among other things, assumptions of the discount rate, estimated return on plan assets and mortality rates. These obligations and related periodic costs are measured using actuarial techniques and assumptions. The projected unit credit method is the actuarial cost method used to compute the pension liabilities and related expenses. All unrecognized actuarial gains and losses, prior service costs and accumulated other comprehensive income are eliminated and the balance sheet liability is set equal to the funded status of the defined benefit plan at acquisition date. In October 2018, a U.K. High Court ruling required pension plans, subject to guaranteed minimum pension rules to amend their pension plan formulas to equalize benefits for men and women to adjust for unequal results previously calculated. The U.K. High Court ruling went on to require pension plans to make back payments subject to plan rule limitations, with interest applied at one percentage point over the Bank of England base rate. The guarantee equalization payment was allowed for by increasing the pension liability. Our portion of the total equalization amount was approximately £0.5 million (or approximately $0.7 million based on GBP: USD exchange rate of 1.33).

The table below sets forth net periodic benefit costs of the plan for the twelve months ended December 31:

	Defined Benefit Plan
	2019			2018
Components of net periodic benefit cost:
Service cost	$	256		$	267
Interest cost		4,069			4,151
Recognized actuarial loss		1,546			2,625
Expected return on plan assets		(7,511	)		(7,339	)
Prior service cost		55			-
Net periodic benefit cost	$	(1,585	)	$	(296	)

The table below sets forth the benefit obligation, the fair value of plan assets, and the funded status as of December 31:

	Defined Benefit Plan
	2019			2018
Change in benefit obligation:
Beginning balance	$	141,104		$	166,063
Service cost		255			267
Interest cost		4,045			4,151
Actuarial loss (gain)		11,214			(9,827	)
Benefits paid		(4,158	)		(3,625	)
Settlements		-			(7,471	)
Currency changes		6,220			(8,454	)
Benefit obligation at December 31	$	158,680		$	141,104

Change in plan assets:
Beginning balance - fair value	$	117,162		$	134,234
Employer contribution		2,629			2,796
Actual return on plan assets		11,791			(2,084	)
Benefits paid		(4,158	)		(3,625	)
Settlements		-			(6,731	)
Currency changes		5,197			(7,428	)
Fair value of plan assets at December 31	$	132,621		$	117,162
Underfunded status at December 31	$	(26,059	)	$	(23,942	)

Based on an actuarial study performed as of December 31, 2019, the plan is underfunded by approximately $26.1 million and the liability is reflected in our consolidated balance sheets as a noncurrent liability and the amount recognized in accumulated other comprehensive loss was approximately $44.7 million.

We apply the “10% corridor” approach to amortize unrecognized actuarial gains (losses). Under this approach, only actuarial gains (losses) that exceed 10% of the greater of the projected benefit obligation or the market-related value of the plan assets are amortized. For the twelve months ended December 31, 2019, the plan’s total recognized loss increased by approximately $5.1 million. The variance between the actual and expected return to plan assets during 2019 decreased the total unrecognized net loss by approximately $4.3 million. The total unrecognized net loss is more than 10% of the projected benefit obligation and 10% of the plan assets. Therefore, the excess amount will be amortized over the average term to retirement of plan participants, not yet in receipt of pension, which as of December 31, 2019, the average term was approximately 10.5 years. The following weighted-average assumptions were used to determine net periodic benefit costs for the twelve months ended December 31:

The following weighted-average assumption was used to determine the benefit obligations at December 31:

The expected long-term return on plan assets was determined based on historical and expected future returns of the various asset classes. The plan’s investment policy includes a mandate to diversify assets and invest in a variety of asset classes to achieve its expected long-term return and is currently invested in a variety of funds representing most standard equity and debt security classes. Trustees of the plan may make changes at any time. The table below sets forth the plan asset allocations of the assets in the plan and expected long-term return by asset category:

Benefit plan payments are primarily made from funded benefit plan trusts and current assets. The table below sets forth the expected future benefit payments, including future benefit accrual, as of December 31, 2019:

We adopted a payment plan with the trustees of the defined benefit plan, in which we would make annual contributions each year through 2030, of approximately GBP 2 million (approximately $2.7 million based on a GBP:USD exchange rate of 1.33). The annual contributions were expected to meet the deficit disclosed in the plan as of April 5, 2013 by December 31, 2030. The trustees are required to review the funding position every three years. Following the pension plan funding valuation as at March 31, 2019 the trustees and the Company have been in discussions regarding a recovery plan would result in a plan to recover the deficit by January 1, 2029. Moving the recovery plan from a 2030 deadline to a 2029 deadline could cause us to increase our contributions. This plan has not been finalized.

The defined benefit plan’s investment strategy is to invest 65% in growth strategy assets and 35% in hedging strategy assets. The growth strategy consists of a highly diversified set of assets, and the hedging component is designed to hedge a significant proportion of the plan’s interest and inflation rate risks. The overall strategy is designed to return a long-term return of 2.6% p.a. above the liability benchmark which is broadly equal to changes in the plan’s liabilities.

The plan’s trustees appoint fund managers to carry out all the day-to-day functions relating to the management of the fund and its administration. The fund managers must invest their portion of the plan’s assets in accordance with their investment manager agreement agreed by the trustees. The trustees are responsible for agreeing these investment manager agreements and for deciding on the portion of the plan’s assets that will be invested with each fund manager. When making decisions, the trustees take advice from experts including the plan’s actuary and also have the option to consult with the Company.

	December 31, 2019
Asset category	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	14,057	$	-	$	-	$	14,057
Equity securities:
U.K.		-		683		-		683
Overseas equities		-		5,909		-		5,909
Emerging markets		-		11,413		-		11,413
Fixed income securities:
Government bonds		-		5,160		-		5,160
Non-government bonds		-		9,906		-		9,906
Index-linked securities:
U.K. treasury securities		-		166		-		166
Other types of investments
Hedge funds		-		39,710		-		39,710
Property		-		3,224		-		3,224
Liability-driven investments		-		42,014		-		42,014
Other		-		379		-		379
Total	$	14,057	$	118,564	$	-	$	132,621

Fair value is taken to mean the bid value of securities, as supplied by the fund managers. All the plan’s securities are publicly traded and highly liquid. The plan does not hold any Level 3 securities. See Note 3 for additional information regarding fair value and Levels 1, 2 and 3.

The investment manager agreements require the fund managers to invest in a diverse range of stocks and bonds across each particular asset class. The stocks held by the plan in a particular asset class should therefore match closely the underlying stocks in the relevant index. We believe that this leads to minimal concentration of risk within each asset class; although we recognize that some asset classes are inherently more risky than others.

We also have pension plans in Asia for which the benefit obligation, fair value of the plan assets and the funded status amounts are immaterial and therefore, not included in the amounts or assumptions above.

We maintain a 401(k) retirement plan (the “Plan”) for the benefit of qualified employees at our U.S. locations. Employees who participate may elect to make salary deferral contributions to the Plan up to 100% of the employees’ eligible payroll subject to annual Internal Revenue Code maximum limitations. We currently make a matching contribution of $1 for every $2 contributed by the participant up to 6% (3% maximum matching) of the participant’s eligible payroll, which vests over an initial four years. In addition, we may make a discretionary contribution to the entire qualified employee pool, in accordance with the Plan.

As stipulated by the regulations of China, we maintain a retirement plan pursuant to the local municipal government for the employees in China. We are required to make contributions to the retirement plan at a rate between 10% and 22% of the employee’s eligible payroll. Pursuant to the Taiwan Labor Standard Law and Factory Law, we maintain a retirement plan for the employees in Taiwan, whereby we make contributions at a rate of 6% of the employee’s eligible payroll.

For the years ended December 31, 2019, 2018 and 2017, total amounts expensed under these plans were approximately $16.3 million, $17.0 million and $14.8 million, respectively.

We maintain a Non-Qualified Deferred Compensation Plan (the “Deferred Compensation Plan”) for executive officers, key employees and members of our Board of Directors. The Deferred Compensation Plan allows eligible participants to defer the receipt of eligible compensation, including equity awards, until designated future dates. We offset our obligations under the Deferred Compensation Plan by investing in the actual underlying investments. At December 31, 2019 these investments are classified as trading securities and are carried at fair value. At December 31, 2019, these investments totaled approximately $12.9 million. All gains and losses in these investments are materially offset by corresponding gains and losses in the deferred compensation plan liabilities.