DEBT

Short-term borrowings and the current portion of long-term debt at March 31, 2016 and December 31, 2015 consisted of the following:



	March 31, 2016			December 31, 2015
Zero-coupon convertible subordinated notes	$	95.0		$	94.5
3.125% senior notes due 2016	325.0			325.0
Debt issuance costs	(0.8		)	(1.0		)
Current portion of capital leases	6.2			5.4
Total short-term borrowings and current portion of long-term debt	$	425.4		$	423.9

Long-term debt at March 31, 2016 and December 31, 2015 consisted of the following:



	March 31, 2016			December 31, 2015
2.20% senior notes due 2017	$	500.0		$	500.0
2.50% senior notes due 2018	400.0			400.0
4.625% senior notes due 2020	642.1			621.6
2.625% senior notes due 2020	500.0			500.0
3.75% senior notes due 2022	500.0			500.0
3.20% senior notes due 2022	500.0			500.0
4.00% senior notes due 2023	300.0			300.0
3.60% senior notes due 2025	1,000.0			1,000.0
4.70% senior notes due 2045	900.0			900.0
Term loan	715.0			715.0
Debt issuance costs	(49.7		)	(51.8		)
Capital leases	62.1			55.5
Total long-term debt	$	5,969.5		$	5,940.3

Senior Notes

As a result of the Acquisition, the Company assumed privately placed senior notes in an aggregate principal amount of $250.0 issued by Covance pursuant to a Note Purchase Agreement dated October 2, 2013. On March 5, 2015, the Company caused Covance to prepay all of the outstanding Senior Notes at 100% of the principal amount plus accrued interest, and a total make-whole amount of $37.4 which was expensed. The Note Purchase Agreement terminated effective March 5, 2015 in connection with the prepayment of the Senior Notes.

During the third quarter of 2013, the Company entered into two fixed-to-variable interest rate swap agreements for its 4.625% senior notes due 2020 with an aggregate notional amount of $600.0 and variable interest rates based on one-month LIBOR plus 2.298% to hedge against changes in the fair value of a portion of the Company's long-term debt. These derivative financial instruments are accounted for as fair value hedges of the senior notes due 2020. These interest rate swaps are included in other long-term assets and added to the value of the senior notes, with an aggregate fair value of $42.1 at March 31, 2016 and $21.6 at December 31, 2015.

Zero-Coupon Subordinated Notes

On March 11, 2016, the Company announced that for the period from March 12, 2016 to September 11, 2016, the zero-coupon subordinated notes will accrue contingent cash interest at a rate of no less than 0.125% of the average market price of a zero-coupon subordinated note for the five trading days ended March 8, 2016, in addition to the continued accrual of the original issue discount.

On April 4, 2016, the Company announced that its zero-coupon subordinated notes may be converted into cash and common stock at the conversion rate of 13.4108 per $1,000.0 principal amount at maturity of the notes, subject to the terms of the zero-coupon subordinated notes and the indenture, dated as of October 24, 2006 between the Company and The Bank of New York Mellon, as trustee and the conversion agent. In order to exercise the option to convert all or a portion of the zero-coupon subordinated notes, holders are required to validly surrender their zero-coupon subordinated notes at any time during the calendar quarter beginning April 1, 2016 through the close of business on the last business day of the calendar quarter, which is 5:00 p.m., New York City time, on Thursday, June 30, 2016. If notices of conversion are received, the Company plans to settle the cash portion of the conversion obligation with cash on hand and/or borrowings under the new revolving credit facility.

Credit Facilities

As part of its financing of the Acquisition, the Company entered into a $1,000.0 term loan. The term loan credit facility will mature five years after the closing date of the Acquisition and may be prepaid without penalty. The term loan balance at March 31, 2016 and December 31, 2015 was $715.0.

On December 19, 2014, the Company entered into an amendment and restatement of its existing senior revolving credit facility, which was originally entered into on December 21, 2011. The senior revolving credit facility consists of a five-year revolving facility in the principal amount of up to $1,000.0, with the option of increasing the facility by up to an additional $250.0, subject to the agreement of one or more new or existing lenders to provide such additional amounts and certain other customary conditions. The new revolving credit facility also provides for a subfacility of up to $100.0 for swing line borrowings and a subfacility of up to $125.0 for issuances of letters of credit. The new revolving credit facility is permitted to be used for general corporate purposes, including working capital, capital expenditures, funding of share repurchases and certain other payments, and acquisitions and other investments. There was no outstanding balance on the Company's revolving credit facility at March 31, 2016 or December 31, 2015.

On January 30, 2015, the Company issued $2,900.0 in debt securities consisting of $500.0 aggregate principal amount of 2.625% Senior Notes due 2020, $500.0 aggregate principal amount of 3.20% Senior Notes due 2022, $1,000.0 aggregate principal amount of 3.60% Senior Notes due 2025 and $900.0 aggregate principal amount of 4.70% Senior Notes due 2045 (together, the Acquisition Notes). Net proceeds from the offering of the Acquisition Notes were $2,870.2 after deducting underwriting discounts and other expenses of the offering. Net proceeds were used to pay a portion of the cash consideration and the fees and expenses in connection with the Acquisition.

On February 13, 2015, the Company entered into a 60-day cash bridge term loan credit facility in the principal amount of $400.0 for the purpose of financing a portion of the cash consideration and the fees and expenses in connection with the Acquisition. The 60-day cash bridge term loan credit facility was advanced in full on February 19, 2015, the date of the Company’s completion of the Acquisition. On March 16, 2015, the Company elected to prepay the bridge facility without penalty.

Under the term loan facility and the revolving credit facility, the Company is subject to negative covenants limiting subsidiary indebtedness and certain other covenants typical for investment grade-rated borrowers, and the Company is required to maintain a leverage ratio that declines over time. From and after the Acquisition Date, the leverage ratio must be no greater than 4.75 to 1.0 with respect to the last day of each of the first four fiscal quarters ending on or after the closing date, 4.25 to 1.0 with respect to the last day of each of the fifth through eighth fiscal quarters ending after the closing date, and 3.75 to 1.0 with respect to the last day of each fiscal quarter ending thereafter. The Company was in compliance with all covenants in the term loan facility and the new revolving credit facility at March 31, 2016. As of March 31, 2016, the ratio of total debt to consolidated trailing 12 month EBITDA was 3.5 to 1.0.

The term loan credit facility accrues interest at a per annum rate equal to, at the Company’s election, either a LIBOR rate plus a margin ranging from 1.125% to 2.00%, or a base rate determined according to a prime rate or federal funds rate plus a margin ranging from 0.125% to 1.00%. Advances under the revolving credit facility will accrue interest at a per annum rate equal to, at the Company’s election, either a LIBOR rate plus a margin ranging from 1.00% to 1.60%, or a base rate determined according to a prime rate or federal funds rate plus a margin ranging from 0.00% to 0.60%. Fees are payable on outstanding letters of credit under the new revolving credit facility at a per annum rate equal to the applicable margin for LIBOR loans, and the Company is required to pay a facility fee on the aggregate commitments under the new revolving credit facility, at a per annum rate ranging from 0.125% to 0.40%. The interest margin applicable to the credit facilities, and the facility fee and letter of credit fees payable under the new revolving credit facility, are based on the Company’s senior credit ratings as determined by Standard & Poor’s and Moody’s, which are currently BBB and Baa2, respectively.

As of March 31, 2016, the effective interest rate on the revolving credit facility was 1.53% and the effective interest rate on the term loan was 1.68%.