Mr Hargreaves says he is selling a portion of his shares in the FTSE 100 company to diversify his holdings and for ‘Financial Planning’ reasons.
He says he remains “proud” of the company he helped build with co-founder Stephen Lansdown.
The often controversial entrepreneur, who helped to fund the Brexit campaign, said: “This is part of a process of long-term Financial Planning to diversify my assets. I remain, and will continue to be, a substantial shareholder in Hargreaves Lansdown.
“I am very proud of the business that I co-founded and helped build."
Mr Hargreaves and Mr Lansdown, both accountants by training, initially set up the company in 1981 trading from a spare bedroom. They sold off the page investments in unit trusts and soon found a willing audience of DIY investors.
The company has grown to become one of the largest fund supermarkets and investment providers in the UK although has faced recent criticism for its role in promoting investment in the failed Woodford funds.
Barclays Capital Securities is handling the sale and will use an accelerated bookbuild offering to institutional investors, meaning much of the holding may be pre-sold.
In a stock exchange notice Barclays confirmed that Mr Hargreaves intended to remain a “significant shareholder for the longer term following the completion of the offering.”
Bookbuilding for the sale is already under way. The sale price of the shares and the final size of the offering will be determined after the books have been sold.