"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," Hargreaves, who co-founded the firm with Stephen Lansdown in 1981, said.
The sale will come just days after a slowdown in net new business growth overshadowed an increase in half-year profit for Hargreaves.
The company declined to comment.
Hargreaves Lansdown has faced a tough year after funds it backed, run by independent investment manager Neil Woodford, were suspended after a liquidity squeeze.
Hargreaves Lansdown executives waived their full-year bonuses and also management fees charged to clients which were trapped in the fund.
Barclays Bank, acting through its investment bank, is bookrunner and Numis Securities is acting as co-bookrunner on the sale.
Peter Hargreaves owned 31.59% of the FTSE 100 company as of Jan. 29, according to Refinitiv data.
His shareholding of 149.86 million shares is worth about 2.56 billion pounds, according to Reuters calculation, based on the Bristol, southwest England-based company's closing share price of 1,708.5 pence on Thursday.
Hargreaves and his family set up a charitable foundation https://www.thehargreavesfoundation.org earlier this year, to be funded through a transfer of shares held by him in the company to the foundation.
The value of the transfers in the first year was pegged at about 100 million pounds, with the intention of further meaningful grants over time.
The sale price of the shares and the final size of the sale will be decided after the books have closed, the bookrunner said.
By Noor Zainab Hussain
