U.S. oilfield services provider ProPetro Holding Corp. said Feb. 24 a board committee had found multiple material weaknesses related to its financial reporting and disclosures.

The audit, which was first disclosed in August, was initially focused on disclosures related to purchases of electric hydraulic fracturing fleets. It was later expanded to include expense reimbursements by executives and transactions involving related parties and potential conflicts of interest.

Although the internal committee has wrapped up fact-finding associated with its audit, the Midland, Texas-based company remains the subject of an investigation by the U.S. Securities and Exchange Commission (SEC), which Reuters first reported in October. An independent accounting firm also continues to examine the board's findings and remediation plan.

The audit committee has not found any items that would require a restatement of previously disclosed financial reports, the company said Feb. 24.

ProPetro released preliminary fourth-quarter results on Feb. 24, estimating revenue of between $431 million and $437 million, up slightly from $425.4 million last year.

The company was recently granted an extension to file its second and third-quarter earnings reports with the U.S. SEC.

On Feb. 24, the company said it will not be able to file its annual report on time.

The firm, which provides hydraulic fracturing services, said it averaged 19.2 frac fleets during the quarter. It also began operations on its first electric frac fleet, which is fueled by natural gas rather than diesel.

Shares were flat in after-hours trading at $9.25.