The 10 accounting firms that had the most public company audit clients in 2023 are the same 10 firms atop the table in auditor market share so far in 2024, with EY leading the way as of Jan. 30.

According to a recent study from Ideagen Audit Analytics, EY audits 971 public companies registered with the Securities and Exchange Commission (SEC), with a total market share of 14.7%. But the Big Four firm’s roster of public company audit clients has shrunk from 1,004 last year.

In fact, for the first time in five years, Audit Analytics observed a decrease in total SEC registrants—the population has dropped 4.9%, from 6,950 public companies in 2023 to 6,607 in 2024.

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As a result, the majority of the top 10 audit firms lost SEC-registrant clients from 2023, the exception being second-place Deloitte & Touche, which gained 13 audit clients over the past year for a total of 900.

Of the 239 accounting firms conducting audits of public companies, the top 10 based on total number of clients and auditor market share, according to Audit Analytics, are:

1. EY: 971 (14.7%)
2. Deloitte & Touche: 900 (13.6%)
3. PwC: 719 (10.9%)
4. KPMG: 605 (9.2%)
5. Marcum: 402 (6.1%)
6. Grant Thornton: 283 (4.3%)
7. BDO USA: 182: (2.7%)
8. BF Borgers: 173 (2.6%)
9. RSM US: 129 (1.9%)
10. Withum: 113 (1.7%)

Keep in mind that those client counts include special-purpose acquisition companies (SPACs), 303 of which were registered with the SEC. Positioning among the top 10 stayed relatively the same compared to last year, with the only change being RSM leapfrogging over Withum for ninth place.

The emergence of SPACs over the past few years has influenced audit market share for firms like Marcum and Withum, which focus heavily on auditing newly formed SPACs, Audit Analytics noted. Therefore, if you remove SPAC clients from the equation, Grant Thornton knocks Marcum out of the fifth spot, while Crowe overtakes Withum for 10th place.

1. EY: 971 (15.4%)
2. Deloitte & Touche: 900 (14.3%)
3. PwC: 719 (11.4%)
4. KPMG: 605 (9.6%)
5. Grant Thornton: 274 (4.3%)
6. Marcum: 253 (4%)
7. BF Borgers: 171: (2.7%)
8. BDO USA: 167 (2.6%)
9. RSM US: 129 (2%)
10. Crowe: 86 (1.4%)

The Big Four firms dominated the market share of large-accelerated filers, auditing 90% of this market, up two percent from last year. EY remained in the lead for an eighth consecutive year with 577 large-accelerated-filer clients. While EY’s client count in this sector decreased by 23 clients since 2023, the firm continues to audit approximately 28% of all large-accelerated filers.

Outside of the Big Four, there were 31 other firms that competed for the remaining 10% of the large-accelerated-filer market, with Grant Thorton holding the largest portion at 4%.

Since last year’s analysis, the population of large-accelerated filers decreased by 3%, according to Audit Analytics.

You can find out more results of the Audit Analytics analysis here.