Syneos Health Inc. stock dropped over 20 percent in after-hours trading after announcing Wednesday that the Securities and Exchange Commission has started an investigation into its accounting procedures.

An earnings release and conference call was previously scheduled for Feb. 28, but the company has delayed it in order to conduct a review about its financial reporting.

The Morrisville-based clinical studies company was notified Feb. 21 by the SEC that it has “commenced an investigation into the company’s revenue accounting policies, internal controls and related matters.”

The SEC has requested that Syneos retains certain documents for the periods beginning with Jan. 1, 2017.

According to a release, the company is fully cooperating with the SEC.

As an additional measure, the audit committee of the company’s board of directors is conducting an independent review of the company’s internal controls and related matters.

This committee is working with the assistance of outside counsel and accounting advisors in order to complete the company’s Form 10-K.

The company has filed a Form 12b-25, Notification of Late Filing, with the SEC and currently expects to file its Form 10-K within the 15-day extension period.

Prior to receiving notice of the SEC inquiry, the company had substantially completed its year-end processes, including those relating to internal controls, with respect to the 2018 financial statements and forecasts for 2019.

The stock is currently at $40.38 Thursday morning, down over 20 percent from Wednesday’s closing price of $52.01.