Citigroup has defeated a $900m (€762m) claim filed against it by an investor who argued that he lost money by relying on allegedly flawed research issued by the firm.

A Citigroup spokeswoman confirmed that an NASD arbitration panel rejected the claim of Donald Sturm, an investor who argued in the case that he held on to nearly 21 million WorldCom shares on the advice of Jack Grubman, the disgraced Citigroup analyst.