The Financial Services Authority (FSA) has revealed the poor practices it found during a review of SIPP providers.
As a result, the regulator has promised further publications on SIPPs and investments, particularly unregulated collective investment schemes (UCIS), over the next year.
Earlier this year, the FSA conducted an investigation of SIPP providers' practices, involving questionnaires sent out to 70 firms, 33 phone interviews and seven visits to businesses.
Yesterday the regulator revealed it found poor due diligence practices on clients' assets and investments, unclear disclosure, and a lack of proper administration procedures.
Milton Cartwright, manager of pensions investment policy at the FSA, said: "We found firms which were not aware of their responsibilities until they had been to a trade body session, and senior management teams with poor knowledge of where the risks in their businesses are.
"There was poor due diligence on investments such as unquoted shares and unregulated collective investment schemes (UCIS), and on introducers.
"Sometimes it was not clear if an investment itself existed. In one case, a client had £10m apparently in unlisted shares, but the provider had no idea where the money was."
Cartwright said some firms had no real procedures for valuing client assets in place, and no proper records of instructions from clients.
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