Shares of MiMedx Group Inc. plummeted 36% toward a four-year low in active premarket trade Thursday, to pace all the decliners before the open, after the therapeutic biologics company said it would have to restate results for the last five years and said its chief financial officer left the company. The company had previously announced that it was investigating accounting treatment of certain sales and distribution practices. The company has concluded that it will restate results for years ended 2012, 2013, 2014, 2015 and 2016, and the results of the first three quarters of 2017. MiMedx said it was withdrawing all prior financial guidance. Separately, MiMedx said former CFO Michael Senken has left the company, effective Wednesday, after 8 1/2-years in the role. Edward Borkowski was appointed interim CFO, effective immediately, until a permanent replacement is found. The stock, on track to open at the lowest level seen during regular session hours since May 15, 2014, has tumbled 35% year to date through Wednesday, while the S&P 500 has gained 3.7%.