Venture-backed companies mature enough to sell shares to the public haven’t been rushing the door. Only 10 companies have floated shares since the start of May, partly the result of the shadow cast by Facebook’s mishandled IPO.

But those that have gone public have had pretty good results. Nine hold gains over their offering price, six with advances of 20% or greater, a peHUB market analysis found. The only loser is Facebook itself.

The top gainers are a broad-based lot. Two of the companies with 20%-plus advances sell software to the enterprise market, not a surprise since enterprise companies have had warm receptions in the public markets all year. Two are in health care or biotechnology, and one is an Internet company. The final one makes semiconductors.

The respectable performance is likely to encourage companies now in the IPO line (some secretly under cover of the JOBS Act). It also might foretell of a coming boost in activity, though the European debt crisis must send shivers up the spine of every startup CEO.

Here is the scorecard of offerings since May 1 listed from best to worst performance, according to data collected by peHUB. We assembled the list of companies from a database maintained by Thomson Reuters, publisher of this blog.

• Supernus Pharmaceuticals, up 133% from an IPO price of $5. Trading at $11.67 with a market cap of $323 million. Is a biopharmaceuticals company.
• WageWorks, up 44% from an IPO price of $9. Trades at $13 with a market cap of $342 million. Provides health care account administration.
• ServiceNow, up 35% from an IPO price of $18. Trades at $24.29 with a market cap of $3 billion. Develops enterprise software.
• Palo Alto Networks, up 23% from an IPO price of 42. Trades at $51.51 with a market cap of $3.5 billion. Makes enterprise security software.
• Kayak Software, up 22% from an IPO price of $26. Trades at $31.67 with a market cap of $126 million. Operates a travel Website.
• Audience, up 21% from an IPO price of $17. Trades at $20.49 with a market cap of $412 million. Develops semiconductors.
• Exa, up 4% from an IPO price of $10. Trades at $10.35 with a market cap of $129 million. Develops technical software.
• Durata Therapeutics, up 3.1% from an IPO price of $9. Trades at $9.28 with a market cap of $164 million. Is into biopharmaceuticals.
• Tesaro, up 2.96% from an IPO price of $13.50. Trades at $13.90 with a market cap of $360 million. Is a biopharmaceutical company.
• Facebook, down 24% from an IPO price of $38. Trades at $28.81 with a market cap of $79 billion. Runs the world’s most recognized social networking site.

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