Largest Audit Firms by Public-Company Clients (2026)

The 4 largest audit firms audit 44% of SEC-registered public companies, but 76% of the large accelerated filers, according to the auditor each company names in its annual report to the SEC. Deloitte & Touche LLP has the most clients, 857 of the 6,720 companies that filed an annual report from October 1, 2025 to September 30, 2026, according to SEC filings. Among large accelerated filers, Ernst & Young LLP audits the most, 485 to Deloitte & Touche LLP's 462, according to SEC filings.

A large accelerated filer is a company with a public float of $700 million or more, as the SEC defines it in Rule 12b-2. Every figure here is a count of companies, read from the cover page of each annual report, where the SEC requires the company to name its auditor and the auditor's PCAOB ID.

The 25 audit firms with the most SEC-registered clients

Each row is one audit firm as the PCAOB registers it, identified by the PCAOB ID the annual report gives. Firms in one network are separate rows: a US firm and its affiliate in another country have different PCAOB IDs, and the office column tells them apart. Companies are counted at their latest annual report in the window.

Rank	Audit firm	PCAOB ID	Office named most often	Registrants audited	Share of registrants	Large accelerated filers	Exchange-listed clients	Source
1	Deloitte & Touche LLP	34	New York, New York	857	12.8%	462	700	SEC
2	Ernst & Young LLP	42	New York, New York	765	11.4%	485	676	SEC
3	PricewaterhouseCoopers LLP	238	Boston, Massachusetts	690	10.3%	445	594	SEC
4	KPMG LLP	185	New York, New York	615	9.2%	366	529	SEC
5	Grant Thornton LLP	248	Dallas, Texas	237	3.5%	82	212	SEC
6	WithumSmith+Brown, PC	100	New York, New York	214	3.2%	3	177	SEC
7	CBIZ CPAs P.C.	199	New York, NY	151	2.2%	6	118	SEC
8	BDO USA, P.C.	243	San Diego, California	143	2.1%	28	116	SEC
9	Crowe LLP	173	Los Angeles, California	95	1.4%	26	88	SEC
10	Baker Tilly US, LLP	23	Minneapolis, Minnesota	92	1.4%	10	80	SEC
11	RSM US LLP	49	Boston, Massachusetts	85	1.3%	23	76	SEC
12	M & K CPAS, PLLC	2738	The Woodlands, TX	66	1.0%	0	22	SEC
13	KPMG LLP	85	Vancouver, Canada	63	0.9%	4	60	SEC
14	Forvis Mazars, LLP	686	Atlanta, Georgia	61	0.9%	14	51	SEC
15	MaloneBailey, LLP	206	Houston, Texas	57	0.8%	1	49	SEC
16	Enrome LLP	6907	Singapore	57	0.8%	0	47	SEC
17	PricewaterhouseCoopers LLP	271	Vancouver, Canada	56	0.8%	12	52	SEC
18	WWC, P.C.	1171	San Mateo, California	50	0.7%	0	42	SEC
19	Kost Forer Gabbay & Kasierer	1281	Tel-Aviv, Israel	49	0.7%	17	45	SEC
20	Fruci & Associates II, PLLC	5525	Spokane, Washington	41	0.6%	0	4	SEC
21	RBSM LLP	587	New York, NY	40	0.6%	0	20	SEC
22	Marcum Asia CPAs LLP	5395	New York, New York	40	0.6%	0	36	SEC
23	EisnerAmper LLP	274	Iselin, New Jersey	38	0.6%	1	27	SEC
24	Deloitte LLP	1208	Toronto, Canada	38	0.6%	8	34	SEC
25	Audit Alliance LLP	3487	Singapore	38	0.6%	0	35	SEC

Download this table (CSV), free. The full dataset, every audit firm named in the window with its PCAOB ID and every spelling of its name that filings used, is one email away.

Who audits the largest companies

The share of companies audited by the 4 largest firms rises with the SEC's filer status, according to SEC filings:

SEC filer status	Registrants	Audited by the 4 largest firms	Share	Source
Large accelerated	2,309	1,756	76%	SEC
Accelerated	863	388	45%	SEC
Non-accelerated	3,410	779	23%	SEC
Not stated	138	1	1%	SEC

392 audit firms signed at least one annual report in the window, and 122 of them signed exactly one, according to SEC filings. The 4 largest are, in order, Deloitte & Touche LLP, Ernst & Young LLP, PricewaterhouseCoopers LLP and KPMG LLP, and the next, Grant Thornton LLP, has 237 clients.

One firm audits most blank-check companies

259 of the registrants file under SIC code 6770, EDGAR's code for blank-check companies. WithumSmith+Brown, PC audits 143 of them, 55%, according to SEC filings, and blank checks are 67% of its own clients. It ranks number 6 by client count and audits 3 large accelerated filers, according to the same filings.

What this means for technology buyers

An audit firm's public-company practice is an engagement business: staffing, budgets, workpapers and independence checks across many clients at once. These guides compare the systems audit and advisory firms run it on, and the ones their clients use to manage audits:

• Engagement management and resource planning for audit firms: scheduling, staffing and engagement economics.
• Audit management systems for financial services: the internal audit side, where findings are tracked to closure.
• Document automation for tax and audit practices: workpapers, requests and confirmations.
• Time and billing software for advisory practices: time capture and billing for professional firms.

Mapping a professional services firm before choosing its systems? The Professional Services Business Architecture Toolkit sets out what such a firm does and how the work flows.

More from Finantrix Atlas

• Fund auditors: who audits US mutual funds and ETFs
• Private fund auditors
• Top broker-dealer firms in the US
• Largest US-listed REITs by total assets

How this list was built

The universe is every company that filed an annual report on Form 10-K, 10-KT, 20-F or 40-F with XBRL financial statements from October 1, 2025 to September 30, 2026, from the SEC's monthly Financial Statement and Notes data sets: 6,720 companies, each counted once, at its latest original report. An amendment does not count as a report, and 25 companies that filed only an amendment in the window are left out.

The data sets carry every XBRL filing. EDGAR's own form index lists 8,741 annual reports and amendments filed in the same months; the 1,063 that the data sets do not carry are, every one, filings EDGAR itself records as having no XBRL, such as the annual reports of asset-backed issuers. The build stops if one is not.

The auditor is the firm the report names in its cover-page XBRL, with its PCAOB ID and the city of the office that signed. Firms are grouped by that ID, not by name, and the name shown is the one filings use most often for it; every spelling is in the dataset. A report naming two firms, as 21 do, credits both. Exchange-listed means listed on a US exchange in the SEC's company ticker file.

Limits

• Companies, not fees or size. A count gives a small company the same weight as the largest. The filer-status table is the size measure, because the public float that companies report is misstated by orders of magnitude for some filers in the SEC's data.
• Who files XBRL. Funds that file on Form N-CSR and asset-backed issuers are outside the universe; fund auditors are ranked separately.
• One firm, one ID. Member firms of one network count separately, so a network's total is larger than any one of its rows.
• The window is the 12 monthly data sets from October 1, 2025 to September 30, 2026. A company that changed auditors appears under the firm its latest report names.
• Engagement partners are not shown. The PCAOB publishes them on Form AP; its website refused automated reads when this page was built, so its terms of reuse could not be confirmed and its data is not used.

Cite this

Free to quote, cite and republish, including the chart, with credit to Finantrix Atlas and a link to this page.

The 4 largest audit firms audit 44% of SEC-registered public companies and 76% of large accelerated filers, according to a Finantrix Atlas analysis of annual reports filed with the SEC from October 1, 2025 to September 30, 2026.

Deloitte & Touche LLP audits 857 SEC registrants, more than any other firm, according to Finantrix Atlas.

Suggested citation: Finantrix Atlas, "Largest Audit Firms by Public-Company Clients," annual reports filed October 1, 2025 to September 30, 2026, from SEC Financial Statement and Notes data sets. https://www.finantrix.com/articles/largest-audit-firms-public-companies

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<a href="https://www.finantrix.com/articles/largest-audit-firms-public-companies"><img src="https://www.finantrix.com/atlas/largest-audit-firms-public-companies.png" alt="Audit firms with the most SEC-registered clients, from Finantrix Atlas"></a>
<p>Chart: <a href="https://www.finantrix.com/articles/largest-audit-firms-public-companies">Finantrix Atlas</a>, from SEC filings.</p>

Frequently asked questions

Q: Which audit firm audits the most public companies? A: Deloitte & Touche LLP, with 857 of the 6,720 companies that filed an annual report with the SEC from October 1, 2025 to September 30, 2026, according to SEC filings.

Q: What share of public companies do the largest audit firms audit? A: The 4 largest audit 44% of SEC registrants and 76% of large accelerated filers, according to SEC filings from October 1, 2025 to September 30, 2026.

Q: Which firm audits the most large accelerated filers? A: Ernst & Young LLP, with 485, according to SEC filings from October 1, 2025 to September 30, 2026.

Q: Who audits blank-check companies? A: WithumSmith+Brown, PC audits 143 of the 259 blank-check companies that filed an annual report with the SEC from October 1, 2025 to September 30, 2026, 55%, according to SEC filings.