Preqin is just the latest sale by serial entrepreneur Mr O’Hare. He co-founded a management consultancy in the 1980s called Goodall Alexander O’Hare & Co after working at Boston Consulting Group.
In 1993, he founded shareholder information service Citywatch, before selling it five years later to Reuters.
Valhalla Ventures currently owns stakes in document automation tool Avvoka and Net Zero Insights, which provides ESG data.
BlackRock is buying the business 100pc in cash, giving Valhalla Ventures substantial financial firepower for further investing and philanthropy.
Mr O’Hare will join BlackRock as vice chair after the deal closes.
Some of Preqin’s 300 employees will also share the remaining £500m, with several expected to become multi millionaires overnight.
The deal will give BlackRock access to valuable financial data on private markets, which is harder to obtain than public data from the stock market.
Martin Small, BlackRock’s chief financial officer, said it would allow the business to push the “democratisation of alternatives” for retail investors.
The fund manager is hoping to use the private markets data to create price indices similar to the FTSE 100, which could unlock a new world for investors.