The latest quarterly Securities and Exchange Commission (SEC) filing of Big Four company Amedisys hints at a potentially significant referral violation.

The Baton Rouge, La.-based company reports that it has just disclosed to CMS referral arrangements which were likely out of compliance with the Stark law. The Stark law governs financial arrangements between physicians and the providers they refer to.

"In May 2012, the Company made a disclosure to CMS under the agency's Stark Law Self-Referral Disclosure Protocol relating to certain services agreements between a subsidiary of the Company and a large physician group. During some period of time since December 2007, the arrangements appear not to have complied in certain respects with an applicable exemption to the Stark Law referral prohibition. The Company intends to cooperate with CMS in its review of this matter," Amedisys' quarterly filing states.

Amedisys declines to speculate on the likely outcome of the disclosure or any resulting liability.

In reaction to the announcement, New York-based global investment firm Jefferies Group downgraded its price target for Amedisys stock from $15 to $12.