Market regulator Sebi has disqualified Cals Refineries from issuing equity shares and any other security for a further eight years, as the company was found guilty in a case involving irregularities in issuance of Global Depository Receipts (GDRs).An interim prohibitory order was imposed on the company in 2011 and the company has already undergone restrictions for two years, while a final order was passed today imposing a ten-year ban on the company from issuance of any securities.The case is related to alleged market manipulation in trading of GDRs — a financial instrument used to raise capital overseas — of certain companies including Cals.However, Sebi noted that Cals had already undergone the prohibition imposed on it for a period of about two years following an interim order in 2011 by the market regulator in view of the GDR manipulation charges against the company.Sebi said the modus operandi adopted by Cals Refineries in conceiving the fraudulent arrangement of GDR issue to defraud investors and also facilitating the unjust enrichment of its promoter at the expense of investors has been fraught with mala fides at every stage of its execution.