Come July, you will be able to freeze your trading account online, like in the case of debit and credit cards, over suspicious access. Markets regulator Sebi on Friday asked brokerages to set up a mechanism allowing investors to voluntarily freeze or block their trading accounts. At present, investors have the option to freeze or block transactions in their demat account, but not in trading a/cs. Market players said though the demat option is available it's hardly used by investors due to lack of information.