Wall Street's love affair with social media is over, and the founders behind several companies in the sector are seeing hundreds of millions of dollars circle the drain.

Facebook (FB) shares are down 47% from their $38 IPO price in May, closing Thursday at just $20.04. Groupon (GRPN) shares have plunged 68% from their IPO price to close at $6.38, and Zynga (ZNGA) shares have fallen 73% to just $2.70.

Those sharp price drops have taken huge chunks out of the on-paper fortunes of social media kingpins.

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Robert Frank of CNBC estimates that some of their losses range from 40% to 80% -- drops that were much more severe than what was seen even in the dot-com bust of 2000.

Here's what happened to the wealth of three social media founders, according to Frank:

Mark Zuckerberg, CEO of Facebook
Zuckerberg's net worth was $19.1 billion right out of the gate on Facebook's first day of trading, and climbed to $20 billion during the stock's initial frenzy. But Facebook shares have crashed, leaving Zuckerberg more than $9 billion poorer. Zuckerberg owns 503.6 million Class B shares and controls nearly 58% of the voting power at the company.

Andrew Mason, CEO of Groupon
His fortune down more than 75% to $300 million as investors have grown increasingly skeptical of Groupon's potential.

Mark Pincus, CEO of Zynga
His stake has fallen to around $270 million from more than $1 billion in the salad days. But Pincus made an early cash grab last April, selling 16.5 million shares at $12 a share for about $200 million. Hopefully he didn't plow that money into shares of Facebook or Groupon.

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