The IPO market is set to be scorching hot this summer.

Chinese ride-sharing company Didi Chuxing Technology Co. made its IPO documents public Thursday, a major step toward its highly anticipated initial public offering. Robinhood Markets Inc.’s public filing is also looming, people familiar with the matter said. Both companies are poised to begin stock-market trading in July.

Fund managers, venture capitalists, bankers and lawyers said they are busier than they have been in decades at this time of year, which is usually quieter. Some claim business is even crazier than during the dot-com boom of the late 1990s.

From June through August, U.S.-listed IPOs could raise upward of $40 billion, some bankers estimate. That would eclipse the previous record of $32 billion over those three months, set last year, according to Dealogic data going back to 1995. That doesn’t include money raised by special-purpose acquisition companies, or SPACs, which were going gangbusters earlier this year but have slowed.

Some bankers said they are working with more than two dozen companies that have confidentially filed for IPOs and are considering starting roadshows to pitch investors in coming weeks.