The words fundraising and fast are not often found together in private equity. In the aftermath of the financial crisis, even the successful firms took years to raise capital. However, in the past 18 months, the most popular firms have raised funds so quickly that investors are struggling to keep up.

Swedish private equity firm EQT officially launched its seventh fund in April and could wrap up fundraising by the summer at its €6.75 billion upper limit, people familiar with the process said. EQT did not return a request for comment.