Nokia (NYSE:NOK) has not had the most enjoyable of Fridays as the company’s stock is sinking following comments in relation to possible compliance issues in relation to certain transactions.

The Finland-based network equipment maker said on Friday that it was examining transactions at Alcatel-Lucent, a former rival it acquired back in 2016. The comments were made in relation to compliance issues at the unit to U.S. authorities.

Nokia added that certain of its practices that led to the aforementioned issues in relation to Alcatel-Lucient business was a cause for concern once the business was integrated into its fold. The Finnish company revealed that it voluntarily reported the matter to regulators, and it planned on cooperating with authorities to resolve the matter.

“To ensure complete compliance we are now scrutinizing certain transactions in the former Alcatel-Lucent business and although this investigation is in a relatively early stage, out of an abundance of caution and in the spirit of transparency, Nokia has contacted the relevant regulatory authorities regarding this review,” Nokia said in an emailed statement to Reuters.

“The resolution of this matter could result in potential criminal or civil penalties, including the possibility of monetary fines, which could have a material adverse effect on our business, brand, reputation or financial position,” it added in a filing to the U.S. Securities and Exchange Commission.

NOK stock is down about 5.4% on Friday.