A pharmaceutical company has filed a lawsuit today against Citigroup alleging it misrepresented the sale of toxic instruments and destroyed evidence in a further example of the US bank's troubles with auction rate securities.

Braintree Laboratories, Braintree Holdings and Braintree Real Estate Management-the Braintree Entities-filed the lawsuit, obtained by Financial News, in a district court of Massachusetts. The company is attempting to recover $33m (€25m).