The Securities and Exchange Commission on Tuesday held auditor Ernst & Young, and two of its partners accountable for missing for more than four years what it said was a “major accounting fraud.”

The SEC said that if EY and its partners had followed auditing standards they would have likely uncovered the fraudulent scheme at Weatherford International US:WFT as early as 2007. The lead EY audit partner at Weatherford, Craig Fronckiewicz, and former tax partner Sarah Adams, have also been suspended from practicing as public accountants.

Ernst & Young, Fronckiewicz, and Adams consented to the SEC’s order without admitting or denying the allegations.

Ernst & Young, one of the Big 4 global audit firms with PwC, KPMG and Deloitte, was ordered Tuesday to pay $11.8 million—$1 million fines and $10.8 million in audit fee give-backs plus interest. EY paid total fines of $9.3 million to the SEC in September for audit partners that got too close to key clients at two public companies, the SEC alleged.

It’s a sizeable fine for an accounting firm. Last year, Grant Thornton was fined $3 million by the SEC and gave back $1.5 million in fees for ignoring red flags and fraud risks while conducting deficient audits of two publicly traded companies.

A spokeswoman from Ernst & Young sent this statement via email: “Audit quality is central to EY and all of our stakeholders. Since the time of the Weatherford audits, and as referenced in the SEC Order, EY has taken significant steps in improving audit quality. We are pleased to put this matter behind us.”

The SEC said Fronckiewicz and Adams repeatedly engaging in improper professional conduct during the audits and quarterly reviews, relying on Weatherford’s unsubstantiated explanations for post-year end accounting adjustments each year instead of verifying the information. Fronckiewicz and his team failed to find out why the company was experiencing a huge unexplained income tax receivable that grew to over $400 million by year-end 2010, the SEC said.

Weatherford allegedly issued false financial statements between 2007 and 2012 that inflated its earnings by more than $900 million in total, according to the SEC. The company allegedly misled investors about its earnings per share, effective tax rate and other key financial information. Two of its executives were also charged. The SEC collected a $140 million fine in September from Weatherford and its executives.

Also read:SEC won’t pursue clawbacks in Weatherford accounting fraud case

The total money collected from Weatherford and Ernst & Young, a total of more than $152 million, will be returned to investors who were harmed by the accounting fraud, the SEC said.

Weatherford restated its financials in February 2012 and then again in July 2012. Weatherford’s second restatement lowered net income by $256 million more for the periods 2007 to 2011 and its third restatement shaved an additional $186 million more from net income for multiple prior periods.