After two days in which stocks rose early in the day but fell back by the close, the S&P 500 finally advanced to a new all-time record high Thursday, with major market benchmarks finishing up about half a percent. Positive comments from Fed chair Janet Yellen helped give investors confidence about the weak economic data that has hit the news lately, and strong performance from Workday (NASDAQ:WDAY), Zulily (NASDAQ: ZU), and Noah Holdings (NYSE:NOAH) helped set the tone for today's record gains.

Workday climbed 15% after the cloud-based human-resources and enterprise software specialist reported strong revenue growth of 74% and a narrower-than-expected loss last night. In an industry that has long been dominated by Oracle (NYSE:ORCL) and SAP, Workday's success even as a small competitor has investors excited about its ability to lure even the largest business customers to its offerings. With so much growth ahead of it, Workday's share-price gains today could just be the beginning for the company. Analysts at FBR Capital Markets agreed with the positive assessment, upgrading the stock today and expressing optimism about Workday's future.

For Zulily, today's 18% gain was just the latest in a series of upward movements, with Tuesday's 36% jump coming after the online daily deal company saw revenue double and net income more than triple. What's particularly surprising is the fact that investors apparently have faith that Zulily won't duplicate Groupon's (NASDAQ:GRPN) experience in daily deals, even though it's hard to see durable barriers to entry that give Zulily a lasting competitive advantage over any other company that comes into the space.

Noah Holdings rose 16% after the wealth-management company for China's elite posted 81% higher revenue on net income that more than doubled. The company doesn't expect that torrid pace to continue forever, but even more modest guidance for 27% to 34% growth in adjusted earnings per share was enough to make investors optimistic about Noah's future. The primary threat to Noah's success is the risk of a reversal of fortune in what many have called an overheating real-estate market in China, but if the company has advocated a diversified investment strategy for its clients, then even a Chinese implosion might not hurt Noah's prospects going forward.

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