Public Company Auditor Market Share: 2014 Update

Who audits public companies? Anyone reading this blog post here on Audit Analytics will most likely be familiar with the Big Four (Deloitte, PricewaterhouseCoopers, Ernst & Young, and KPMG), who dominate the market share of public companies in the US and around the world. But what other audit firms have significant market share? When we dig into the details, some interesting patterns emerge.

We recently performed an in-depth analysis of the auditor market share for companies registered with the SEC. (The complete breakdown is included at the bottom of this post.) One of the many interesting results of the analysis was that a clear stratification emerged between the largest companies, mid-sized companies, and the smallest companies.

As you can see from the table below, the market for audit services changes enormously from the top to the bottom, as measured by company size. This is consistent with what we might expect. The large publicly traded company in your town is almost certainly audited by one of the Big Four, or at least one of the Global Six (the Big Four plus Grant Thornton and BDO). The local pet store, on the other hand, is probably audited by Joe & Suzy Q, CPAs. But the starkness of the stratification is nevertheless very interesting.


Only 28 audit firms provide audit services to 1,771 large accelerated filers. But the Global Six audit 97.6% of those companies. About 100 different firms audit accelerated and non-accelerated filers, with the Global Six commanding 77.4% and 70.2% of the market share, respectively. As you can see, the smaller the companies, the less the Big Four and Global Six dominate the market.

Further, when we get down to Smaller Reporting Companies the market for audit services explodes. While only 28 firms served all 1,771 large accelerated filers, a whopping 420 different firms provide audit services to 3,324 smaller reporting companies, and the Global Six account for only about 10% of the Smaller Reporting Company market.

The infographic below shows a complete breakdown of the US SEC auditor market share. (Click on the image to expand.)