Britain's financial watchdog has formally ended its inquiry into the false market rumours which hit shares in Halifax Bank of Scotland in March.
The Financial Services Authority (FSA) said it found no evidence that the rumours were spread as part of a 'concerted attempt' by individuals to profit by manipulating HBOS's shares.
The FSA and Bank of England were forced to step in with public statements of reassurance after rumours of a funding crisis sent the bank's shares tumbling nearly 20% on March 19.
The Financial Regulator had been working with the FSA as it was also looking at some share dealings after a plunge in financial shares on St Patrick's Day.
The FSA said it had not been able to show how much impact the HBOS rumours had, as there broader worries on the day. 'Despite the likelihood that the rumours contributed to the fall in the share price, the FSA has not uncovered evidence that they were spread as part of a concerted attempt by individuals to profit by manipulating the share price,' it said.
The FSA said it spoke to 'a number' of market participants at banks, broker dealers and hedge funds, scrutinised trading records and reviewed emails and messages during its probe.
