ClickZ reports that desktop-search company Copernic is backing off Mamma.com's acquisition offer, citing a Securities and Exchange Commission (SEC) investigation into the desktop- and meta-search company. The SEC is looking into trading in Mamma.com's securities, financial reporting and internal controls.

Copernic's decision was apparently brought on by Mamma.com's announcement last week that the SEC inquiry had been formalized.

It had expected to close the deal before the end of May and is now considering whether it's due any break-up fees.