The latest generation of Silicon Valley start-ups is now sprinting to the public markets, raising hopes among large and small investors eager to invest in these high-profile, fast-growing firms.

But the class of 2019 is far different from its predecessors. These companies, including gig economy darlings like Uber and Lyft, are generally older and larger, powered for years by billions of dollars of private money that has reshaped the start-up world.

The additional maturity of the companies may curb wild swings — both big gains and big losses — for new investors.

But it could also mean that the companies’ fastest phases of growth are behind them. As a result, there is an increased risk that in this wave of tech I.P.O.s, an elite group of investors, like sovereign wealth funds and venture capitalists, will grab a larger share of the winnings compared with new investors.