Syneos Health Inc. /zigman2/quotes/207981284/composite SYNH -0.61% revealed Wednesday afternoon that the Securities and Exchange Commission is investigating its accounting procedures. Trading was paused before the news was announced, and shares fell 23% in after-hours action after trading restarted. In a news release, the biopharmaceutical-services company said that it was delaying the release of its earnings results to allow additional time to review the company's internal controls over financial reporting after receiving notification of an investigation by the SEC on Feb. 21. The SEC "has commenced an investigation into the Company's revenue accounting policies, internal controls and related matters, and the SEC has requested that the company retain certain documents for the periods beginning with January 1, 2017," the announcement reads. "The company is fully cooperating with the SEC." Syneos shares closed Wednesday up 0.8% at $52.01, giving it a market capitalization of about $5.4 billion. The stock has gained 45.3% in the past 12 months, as the S&P 500 index /zigman2/quotes/210599714/realtime SPX -0.39% has gained 1.8%.