Shares of stock and commodity exchanges and depositories were trading mixed in the morning trade on Friday. Shares of these companies have been in focus ever since the market regulator Securities and Exchange Board of India (Sebi) introduced new margin rules that came into effect from September 1. According to the new rules, stockbrokers will have to report the upfront margin collected and available with them from their clients – both for sell and buy trades, and failure to do so will attract a penalty. The stocks lying in the investors’ demat account, which were equivalent to margin available till