Two days of solid performance from the stock market finally gave way to declines on Wednesday, as investors focused on the possibility of a return of long-range inflationary pressures and expressed concerns about whether stocks can keep rising even after earnings season ends. Despite the downward pressure that sent major market benchmarks down around half a percent, zulily (UNKNOWN:ZU.DL), Tandem Diabetes Care (NASDAQ:TNDM), and Millennial Media (UNKNOWN:MM.DL) all jumped sharply today.

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The 9% gain for zulily came amid a day of extreme volatility for the online retail company. The stock initially sank by more than 10% as the expiration of its post-IPO lock-up period allowed some of its shareholders to sell shares if they wanted. But those losses quickly evaporated as those who were expecting a more dramatic downward move were apparently thwarted in their dreams of profits, with Fool contributor Jeremy Bowman concluding that a classic short squeeze helped contribute to zulily's gains. Going forward, zulily will have to prove its success or failure on the fundamentals now that IPO-related share liquidity concerns are off the table.

Tandem Diabetes Care jumped 12% as the company got an analyst upgrade. Interestingly, the analyst actually reduced its price target on the stock, but the recommendation came after a 40% decline in shares of the diabetes medical-device specialist over the past two months. Whether Tandem Diabetes Care will be able to realize its goal of creating diabetes-monitoring equipment that can dramatically increase the quality of life for those suffering from the disease is uncertain at this point. Yet with the incidence of diabetes on the rise across the nation, companies like Tandem Diabetes Care have a golden opportunity to make money and make a real difference for diabetes sufferers.

Millennial Media rose 8%, regaining just a bit of the ground it lost last week after a disappointing quarterly report. In response to the share-price plunge, Millennial Media CEO Michael Barrett made a major insider purchase of almost 300,000 shares worth about $1 million and boosting his stake in the company by roughly half. Confidence among executives is always promising, especially in light of the departure of Millennial Media's CFO. But after having disappointed investors on multiple occasions, Millennial Media needs to deliver stronger results next quarter if it wants to have any chance of sustaining its still-rich valuation based on forward earnings estimates.