The account was previously held by MHP Communications, which continues to represent SEI’s Institutional Investors and Investment Managers divisions.
MRM said it will "develop and implement a proactive PR programme that helps raise the profile of the business and its senior team among private banks, wealth managers and private client investment management companies".
Activity will include arranging media meetings, placing opinion articles in key media titles and creating 'thought leadership' campaigns, the agency said.
Brett Williams, managing director at SEI Wealth Platform, UK Private Banking, said: "Regulation and structural factors have brought substantial change to the wealth management industry in recent years. MRM has unrivalled experience in the financial services space, and we are looking forward to having it help us grow our profile among private banks and other institutions in the UK."
MRM founding director Richard Wheat said: "SEI is an exciting business and a recognised leader in helping wealth managers look after their clients’ money through the use of innovative technology. We are thrilled to be working with the team to help raise the profile of the business across a range of media in the UK."
Separately, yesterday (Wednesday) MRM hosted the first of a new series of events aimed at "raising the level of debate in the financial services industry". It featured pensions minister Steve Webb and was moderated by former BBC journalist Declan Curry.