Credit Suisse, one of the biggest operators of a 'dark pool', reached a tentative agreement to pay around $85 million to New York and federal authorities to resolve allegations of wrongdoing in its private trading venue, according to a person familiar with the matter.

Credit Suisse is expect to pay about $30 million in fines to the New York Attorney General and around $55 million in fines and the return of funds tied to the alleged wrongdoing to the Securities and Exchange Commission, the person said.