The old investment adage to avoid initial public offerings has held up this year, as many stocks are trading well below their IPO prices.

Barron's looked at 18 companies that made their U.S. stock-market debuts in 2026, including marquee offerings like SpaceX, Cerebras Systems, Innio, Madison Air Solutions and Jersey Mike's, found that 15 of them are below their offering prices. Many are down 50% or more.

SK Hynix, already public in South Korea, made its U.S. debut in July through an offering of American depositary shares. That stock also is trading below its U.S. offering price in July.

Why do IPOs often falter? Companies that come public often are in hot industries, and carry high valuations to reflect investor optimism. That enthusiasm often wanes, however. This year, some deals were keyed off the AI buildout and enthusiasm for that trend has faded.

There are some winners, notably Arxis, a defense contractor with an aerospace focus; Pershing Square, Bill Ackman's investment management company, and Bending Spoons, the rollup of mature tech companies like AOL.

Give Berkshire Hathaway some credit. The company headed now by CEO Greg Abel picked the right deal when it invested $600 million in Bending Spoons at the July IPO at $29 a share. The stock traded recently at $45, up 55%. In October, Berkshire bought another $330 million of stock at $33.

Berkshire rarely buys IPOs -- reflecting former CEO Warren Buffett's well-founded aversion to them. It participated in Snowflake's IPO in 2020.

Looking at some of the larger deals, SpaceX trades around $131, against an IPO price of $135; Cerebras at $82, less than half its IPO price of $185; and SK Hynix at $124, versus its U.S. offering price of $149.

One of the better ways to play IPOs in a diversified way is through the Renaissance IPO ETF. It adds newly public companies every three months as part of a regular rebalancing and companies cycle out after three years. Individual holdings are capped at a 10% weighting at rebalancing.

Its largest holdings now are SpaceX at nearly 10%, followed by SK Hynix and Astera Labs, both at more than 7%. The ETF, now around $45, is off about 2% so far this year.

Be careful about SK Hynix ADRs. While chip stocks have come under pressure, SK Hynix's U.S. shares trade at a big premium to the Korean shares that Barron's estimates is close to 50%.

Busted IPOs also can be a good place to look for values, and there are many companies to comb through this year.