HSBC Hong Kong's online stock trading experienced its third glitch within a year on Monday, according to a report by Chinese-language Ming Pao Daily.

An HSBC customer reported to the daily that his sell order placed on the bank's online stock trading system wasn't executed, the media report said, adding that the customer received an SMS confirming the execution of the order Monday morning but got another short message at 9pm on the same day saying the order hasn't been executed and has been canceled.

The customer was quoted as saying that the bank fails to give an explanation and detail compensation for the monetary loss involved.

HSBC said they are investigating the incident and will provide a report to the Ho Kong Monetary Authority, according to the media report. The bank said it has no idea the number of customers affected, but will call each affected customer to apologize, the media report noted.

HSBC doesn't rule out the possibility of a system glitch, said the report, adding that the bank apologized and promised compensation if the bank is responsible for the glitch after investigation.