With an aim to check frauds and help it probe the suspected fraudulent activities, market watchdog Sebi may prescribe a code of conduct for key executives of market players such as brokerages and merchant bankers. Sebi is also considering asking the market intermediaries to notify one or more key executives to be held responsible for any violation of norms, so that the entire firm does not face the risk of regulatory actions. Sources in the know said that the move follows growing concerns over some employees indulging into activities like fraud against the clients, front-running, circular trading and manipulating share prices through rumour mongering.