James Hay has seen revenue decrease from £18.7m in the first half of 2012 to £18.2m in the first half of 2013.
RDR created "massive opportunities" for Mattioli Woods as it saw revenue increase by 14.3 per cent to £23.4m.
MC Trustees is concerned about the popularity of so-called esoteric investments and their impact on investors and Sipp providers.
Sipp provider Xafinity has seen a 108 per cent increase in the number of new property Sipps being set up.
The Financial Conduct Authority has stated that the policy statement for the Sipp capital adequacy reform will be issued at the end of the year.