At this pace, the IPO market could exceed last year's $39 billion, PwC said.

It noted that five of the latest half's offerings -- all backed by financial sponsors -- were for more than $1 billion. As a group, the five raised $10.9 billion, or 45%, of total year-to-date proceeds. They included offerings of Argentina-based Arcos Dorados Holdings, at $1.2 billion, and Netherlands-based Yandex N.V., at $1.3 billion.

"Private equity and venture capital firms are continuing to lead the IPO market, succeeding in generating returns on their investments through new listings," Leveque added. "There were a number of high-profile companies backed by financial sponsors that went public in the quarter. Strong interest generated by these companies is an important driver of future financial sponsor-backed deals."

Financial sponsor-backed IPOs continued their leadership of the U.S. IPO market during the second quarter, contributing 80% of total value with $9.6 billion in proceeds and approximately 66% of volume with 31 of the quarter's 47 IPOs.