At least five stock brokers have come under regulatory scanner for siphoning off securities and funds worth over Rs. 500 crore from investor accounts for personal gains to foreign locations, including Switzerland and Singapore, as also for private ventures. All the five brokers are based in the national capital region and at least two of them have already faced market regulator SEBI's ire for various discrepancies. A senior SEBI official said, these brokers diverted the money from the accounts of their clients for personal gains, while one of them is believed to have been running an internet-based scam for luring investors with promise of huge returns in less time.SEBI suspects that the top executives of these brokerage firms could have been hand-in-glove with the promoters in siphoning off the investors' money, as many of them have become untraceable and the show-cause notices served to them have returned undelivered.