4. Credit Agreement

In connection with our acquisition of HDI, we entered into a five-year, revolving and term secured credit agreement, which we refer to as the 2011 Credit Agreement, with certain financial institutions and Citibank, N.A. as Administrative Agent. In May 2013, we amended and restated the 2011 Credit Agreement and entered into a $500 million five-year, amended and restated revolving credit agreement, which we refer to as the 2013 Credit Agreement.

The 2013 Credit Agreement provides for an initial $500 million revolving credit facility, and, under specified circumstances, the revolving credit facility can be increased or one or more incremental term loan facilities can be added, provided that the incremental credit facilities do not exceed in the aggregate the sum of (a) $75 million plus (b) an additional amount not less than $25 million, so long as our total secured leverage ratio, calculated giving pro forma effect to the requested incremental borrowing and other customary and appropriate pro forma adjustment events, including any permitted acquisitions, is no greater than 2.5:1.0.

The 2013 Credit Agreement contains certain customary representations and warranties, affirmative and negative covenants, and events of default. The 2013 Credit Agreement requires us to comply, on a quarterly basis, with certain principal financial covenants, including a maximum consolidated leverage ratio reducing from 3.50:1.00 to 3.25:1.00 over the next five years and a minimum interest coverage ratio of 3.00:1.00.

The interest rates applicable to the revolving credit facility are, at our option, either (a) the LIBOR multiplied by the statutory reserve rate plus an interest margin ranging from 1.50% to 2.25% based on our consolidated leverage ratio, or (b) a base rate (which is equal to the greatest of (a) Citibank’s prime rate, (b) the federal funds effective rate plus 0.50% and (c) the one-month LIBOR plus 1.00% plus an interest margin ranging from 0.50% to 1.25% based on our consolidated leverage ratio). We will pay an unused commitment fee on the revolving credit facility during the term of the 2013 Credit Agreement ranging from 0.375% to 0.50% per annum based on our consolidated leverage ratio.

Our obligations under the 2013 Credit Agreement may be accelerated upon the occurrence of an event of default, which includes customary events of default including, without limitation, payment defaults, failures to perform affirmative covenants, failure to refrain from actions or omissions prohibited by negative covenants, the inaccuracy of representations or warranties, cross-defaults, bankruptcy and insolvency related defaults, defaults relating to judgments, defaults due to certain ERISA related events and a change of control default. As of March 31, 2014, we were in compliance with all the terms of the 2013 Credit Agreement.

Borrowings under the 2013 Credit Agreement were used to refinance the outstanding principal and unpaid interest of $323.8 million and $1.1 million, respectively, under the term loan facility of the 2011 Credit Agreement. We paid lender fees of $2.9 million in connection with amending and restating the Credit Agreement.

The interest expense on revolving debt and commitment fees on unused revolving credit facility are as follows (in thousands):

	March 31,
	Three months ended
	2014		2013
Interest expense	$	1,164	$	2,662
Commitment fees	$	328	$	117

At March 31, 2014 and December 31, 2013, the unamortized balance of deferred origination fees and debt issue costs were $8.5 million and $9.0 million, respectively. For the three months ended March 31, 2014 and 2013, we amortized $0.5 million and $0.9 million, respectively, of interest expense related to our deferred origination fees and debt issue costs.

As part of our contractual agreement with a client, we have an outstanding irrevocable letter of credit or Letter of Credit for $4.6 million, which we established against our existing revolving credit facility.