Source: Sharecast
New York-based HPS, which has around $148bn in client assets, is a specialist in private credit, a core growth market for BlackRock.
Under the term of the deal, the two firms will form a new private financing solutions business unit led by HPS founders Scot French, Michael Patterson and Scott Kapnick, formerly co-head of investment banking at Goldman Sachs.
All three will also join BlackRock’s global executive committee.
BlackRock will pay $9.3bn in stock when the deal closes before paying a further 2.9m shares - currently worth $3bn - in five years’ time, dependent on certain financial targets.
BlackRock, the world’s largest money manager, said: "Durable global growth will require higher volumes of debt financing and markets are increasingly looking to private capital as an answer.
"The addition of HPS will position BlackRock to connect companies of all sizes."
Larry Fink, founder and chief executive, added: "Together with the scale, capabilities and expertise of the HPS team, BlackRock will deliver clients solutions that seamlessly blend public and private."
Kapnick called the deal "an important milestone in our drive to become the world’s leading provider of private financing solutions".
"Our partnership with BlackRock will further strengthen our position in this fast growing but increasingly competitive market."
As at 1300 GMT, shares in BlackRock were down nearly 1% in pre-market trading.
The acquisition of HPS is the latest in a series of deals by BlackRock.
In June, it agreed to buy UK data provider Preqin in a deal worth around $8bn, a few months after snapping up Global Infrastructure Partners for $12.5bn in cash and stock.