Concentration of Credit Risk

3 Months Ended

Oct. 28, 2017

The Company’s customer base is highly concentrated, with its top five customers accounting for approximately 74.9% of its total contract revenues during each of the three months ended October 28, 2017 and October 29, 2016. Customers whose contract revenues exceeded 10% of total contract revenues during the three months ended October 28, 2017 or October 29, 2016 were as follows:



	For the Three Months Ended
	October 28, 2017	October 29, 2016
Comcast Corporation	21.8%	15.1%
AT&T Inc.	19.0%	29.0%
CenturyLink, Inc.	18.9%	15.7%
Verizon Communications Inc.⁽¹⁾	10.7%	9.4%

Customers whose combined amounts of trade accounts receivable and costs and estimated earnings in excess of billings, net (“CIEB, net”) exceeded 10% of total combined trade receivables and CIEB, net as of October 28, 2017 or July 29, 2017 were as follows (dollars in millions):



	October 28, 2017			July 29, 2017
	Amount		% of Total	Amount		% of Total
Comcast Corporation	$	170.8	22.9%	$	159.7	21.3%
CenturyLink, Inc.	$	130.1	17.4%	$	136.1	18.1%
Verizon Communications Inc.⁽¹⁾	$	84.3	11.3%	$	73.7	9.8%
AT&T Inc.	$	83.7	11.2%	$	87.1	11.6%
Windstream Corporation	$	72.0	9.6%	$	84.7	11.3%

⁽¹⁾For comparison purposes in the tables above, amounts from Verizon Communications Inc. and XO Communications LLC’s fiber-optic network business have been combined for periods prior to their February 2017 merger.

The Company believes that none of its significant customers were experiencing financial difficulties that would materially impact the collectability of the Company’s trade accounts receivable and costs in excess of billings as of October 28, 2017. See Note 4, Accounts Receivable, and Note 5, Costs and Estimated Earnings in Excess of Billings, for additional information regarding the Company’s trade accounts receivable and costs and estimated earnings in excess of billings.