This article originally appeared on informed-merchant.com, a blog started by one of our founders, Sean, before he started FeeFighters.

This is a list of the largest ISOs in the country which includes only companies that do not do any of their own processing.  This is based on data from the Nilson Group for the year ended December 31, 2005.

Rank	Company	Volume ($M)	Transactions (M)	Merchants
1	EVO Merchant Services	9,459	163.4	112,930
2	Verus Financial Management	8,087	100.9	65,777
3	Innovative Merchant Solutions	7,500	56.0	200,000
4	Retriever Payment Systems	7,200	88.9	95,000
5	First American Payments Systems	6,781	102.3	93,257
6	Business Payment Systems	5,700	90.0	40,000
7	MSI Merchant Services	4,116	60.5	48,226
8	United Bank Card	3,650	45.4	39,797
9	Texas DCS	3,120	45.4	31,147
10	Cynergy Data	3,065	57.4	36,391
11	Payment Processing	2,323	33.3	10,255
12	North American Bancard	2,321	27.8	32,153
13	TermNet Merchant Services	2,321	27.5	15,444
14	Calpian	2,060	29.2	32,000
15	Mercury Payment Systems	1,859	54.0	7,112
16	Cocard Marketing Group	1,830	29.9	20,720
17	Electronic Merchant Systems	1,700	20.0	18,900
18	Electronic Data Resources	1,600	25.3	23,000

Source: The Nilson Report