The Surrey-based firm has 19 advisers and specialises in collective and structured investments, inheritance tax, retirement planning and corporate benefits.
Sigma managing director Julian Milner says: “Following extensive research for a platform proposition to fit with our truly independent ethos, Nucleus quickly became the clear winner.
“No other platform was able to offer us real tangible, benefits to our business such as total open architecture and shared ownership.”
Nucleus business development director Philip Martin says: “Our proposition allows high quality advisers to align themselves more closely with their customers by offering them a truly transparent proposition that they own and control.
“We continue to be encouraged by the quality and diversity of adviser firms who are keen to share in the Nucleus vision.”