Banks and building societies are failing to give their customers good investment advice, consumer group Which? said today.
Which? said four of the 37 high street banks and building societies its researchers visited gave good advice on investing a lump sum.
The remaining 33 recommended products without properly explaining the risks or missed basics of good advice.
The researchers posed as retired savers with £55,000 to re-invest from a maturing one-year fixed rate bond, which had paid a return of 7%.
The group said 21 out of the 37 advisers suggested the researcher put some money into products referred to as "capital-guaranteed", but eight wrongly said these funds posed no risk.
Six advisers recommended an investment bond, but failed to adequately explain the risks involved.
Fourteen did not mention the Financial Services Compensation Scheme, which pays redress to consumers if they lose money when a firm goes under.
Only one adviser suggested the researcher split the money between two institutions to avoid going over the £50,000 compensation limit that is paid by the FSCS.
Peter Vicary-Smith, chief executive of Which?, said: "It's disappointing to see yet more evidence that the way many banks treat their customers hasn't improved since our taxes were used to bail them out.
"Our research, evidence we've heard at the Future of Banking Commission and calls to our Money Helpline show that consumers are being convinced to take out high-risk products that they simply don't understand.
"Banks and building societies need to buck up their ideas and make sure that their sales practices don't exploit consumers by encouraging their staff to recommend inappropriate products."
A British Bankers' Association spokesman said: "Which? took a small sample and tested its views against them: this is not valid research.
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"Banking is a relationship business. Banks' investment recommendations are the result of a two-way process: the advice can only be as good as the information received.
"It is unclear from Which?'s conclusions that it gave the subjects of its study an opportunity to demonstrate the care and integrity with which they approach customers."
