HSBC said it was investigating reports that customers in Hong Kong managed to buy the Swiss franc below market rates, due to a technical glitch.Customers were apparently allowed to take advantage of the mistake, when an on-line bank failed to keep up with the Swiss franc's sharp gains in the wake of the Swiss National Bank's (SNB)decision to remove the cap on the currency.The Hong Kong Economic Journal and the Apple Daily cite unidentified bank customers, who claimed to have made profit during a two-hour period. An HSBC customer cited by the Apple Daily is said to have made HK$4000 (just under £340) after buying HK$50,000 of the Swiss currency.A source cited by the Apple Daily claimed to have purchased the Swiss currency at HK$8.26 per franc, when the market rate was between HK$8.80 to HK$9, while another customer claimed to have made a 21% profit on currency transactions.The removal of the currency cap saw the Swiss franc rally against the euro, gaining as much as 41% at one point in the session, although it finished higher by a lesser 19%.