The Financial Conduct Authority warned almost 80 per cent of advisers in the defined benefit market about their transfer advice last year as the regulator continued its crackdown.
In October Debbie Gupta, director of financial advice at the FCA, said the watchdog had written to more than half of the 2,500 advice firms in the defined benefit market expressing concerns.
A freedom of information request submitted by consulting firm Buck has confirmed the watchdog wrote to 1,841 advisers about "potential harm" in their transfer advice - almost 80 per cent of the market.
The letters were part of the FCA's growing effort to crack down on poor advice in the sector, following a survey published in June in which it found too much of the advice on defined benefit transfers it had seen was "still not of an acceptable standard".
Advisers contacted by the FCA were given between one and two months to rectify the risks identified in their transfer advice, or face further scrutiny from the regulator.
The watchdog is set to conduct a further round of assessments in 2020 and has previously said if it finds concerns persist further action against firms is "likely".
In 2017 the FCA's suitability review found only 47 per cent of the DB transfer cases it analysed were suitable, with 36 per cent being "unclear".
This compared to the 90 per cent suitability the FCA found in the pensions accumulation advice market and 91 per cent in the retirement income advice market.
Mark van den Berghen, principal and senior consulting actuary at Buck, said: "This latest information from the FCA is alarming and should worry all involved – providers, advisers, and scheme members.
"If the FCA fears that the majority of firms advising on DB transfers are giving potentially harmful advice, there are some serious questions to be asked of the industry."
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