The Big Four accounting firms are coming off a big year and headed for another, perhaps even bigger one. And if you're a corporate client, it's likely going to cost you, according to analysts studying this increasingly concentrated industry.

Big4.com, a leading source for information about the largest accounting firms—PricewaterhouseCoopers, Deloitte, Ernst & Young and KMPG, all private partnerships—recently released a report showing the firms' revenue grew collectively by 9% in 2011, to $103 billion. That represents a major rebound from the recession years of 2009 and 2010, and tops the previous Big Four revenue record of $101 billion in 2008.

The Big4.com study shows PwC reclaimed the top spot in 2011 as its revenue grew 10% to $29.2 billion, passing Deloitte, whose $28.8 billion in revenue was up just 8.4%. KPMG showed the strongest growth, up 10.1% to $22.7 billion, moving it closer to third-ranked Ernst & Young, which had $22.9 billion in revenue, a gain of just 7.6%.