When Snap Inc. (SNAP) - Get Report made its blockbuster debut on the public markets in March, co-founders Evan Spiegel and Bobby Murphy had plenty to smile about. 

The 20-something executives behind the disappearing message app Snapchat had just completed the largest tech IPO since Chinese e-commerce giant Alibaba (BABA) - Get Report in 2014, valuing the company at $33 billion.

In a single day, the pair made a combined $2.8 billion from the offering, putting their net worths at roughly $5.4 billion each, according to Fortune. Before the IPO, their stakes in the company were worth about $4 billion each, based on the last private valuation of the company. 

Their futures looked bright, until suddenly, it wasn't. Snap's stock value has been cut in half since the IPO, as it has struggled to maintain the rapid user and revenue growth shown its IPO prospectus, Facebook Inc.'s (FB) - Get Report endless copycat products began to eat away it its business and it remains unclear whether it's successfully courting advertisers on Snapchat. As a result, shares have dipped below Snap's $17 IPO price, while analysts have begun to grow impatient with the company's lack of progress. 

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Snap failed to meet expectations across the board in its first quarterly earnings back in May, and earlier this month, it reported another dismal quarter in which revenue, earnings and user growth all disappointed.

Shares fell more than 6% in the week following its second-quarter earnings report, shaving about $300 million each from Spiegel and Murphy's net worths. Snap's stock has since pared some of its losses, helped by lower-than-expected volatility from the recent lockup expirations. As a result, the cofounders' net worth has bumped back up to $3.3 billion each from the post-earnings low of $2.8 billion, according to Forbes real-time net worth tracker.

That said, even though each are worth $3.3 billion, the pair have still lost more than one-third of their fortune, or $2.1 billion each, since March. They're now worth considerably less than before they went public. 

Don't feel too bad for the pair -- Spiegel and Murphy's wealth still places them among the world's youngest self-made billionaires (Facebook (FB) - Get Report CEO Mark Zuckerberg, who's six years older than Spiegel, dwarfs them with a $70 billion net worth, though). 

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And the pair have at least the rest of the year to turn their paper fortunes around. On the second quarter earnings call, Spiegel made a point of saying that he and Murphy would not be selling any of their Snap shares this year, reassuring investors who might be concerned about a flood of Snap shares hitting the markets soon post lockup expiration. 

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"We believe deeply in the long-term success of Snap," Spiegel said.

Ultimately, all isn't bad for Snap's cofounders -- especially Spiegel. He just celebrated his marriage to Victoria's Secret model Miranda Kerr and is probably still riding high from a three-week yacht vacation with friends in the Ionian Sea, much to the chagrin of investors. Ross Gerber, CEO of investment management firm Gerber Kawasaki, said Spiegel and Murphy's arrogance is partly to blame for the company's missteps.

"These are 26-year-old kids with untold amounts of money," Gerber said. "They built a $10 billion app and cashed out, but it's not good to be a shareholder."

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Editors' pick: Originally published Aug. 25.