Conventional wisdom suggests that the health-care sector is a boring, defensive place to park your investment dollar. After all, health-care spending is relatively non-cyclical and benefits from a high degree of inelastic demand (i.e., price increases have a small impact on consumption). While that might be true at a high level, competition for that spending is extremely fierce, and regulatory risks create incredible uncertainty and volatility for investors in many individual health-care stocks. The industry stayed true to its defensive reputation in today's down market, as the aggregate industry rose despite a broader market sell-off. Let's look at a few companies that led the pack higher.

After a collapse of epic proportions yesterday, Peregrine Pharmaceuticals (Nasdaq: PPHM) shares bounced back with a 46% rally today. While a large move like that might sound encouraging, consider that the $0.54 boost shares saw today would have been only a 10% gain two days ago. Shares were slammed 78% on Monday after the company disclosed that its phase 2 data for cancer drug Bavituximab wasn't reliable. With the company's future largely tied to the success of this drug, investors would be wise to steer clear of this stock until we receive more clarity into the data integrity issues behind this disclosure.

Also flying high, albeit at a much lower altitude, was Antares Pharma (Nasdaq: ATRS). Shares rose 7% after releasing positive results from a clinical trial of its VIBEX MTX auto-injection system. The trial involved 101 patients using Antares' VIBEX Medi-Jet drug delivery device to self-administer various dosages of anti-rheumatic drug Methotrexate. The tests went off without a hitch, with every patient successfully using the device and the company reporting that nearly all patients said in a follow-up questionnaire that the device was easy to use. The data should bode well for Antares as it files a New Drug Application with the FDA in the first quarter of 2013. Having a fully homegrown product in its arsenal is important of Antares, which relied on partner Teva (NYSE: TEVA) for about 50% of revenue last year. Teva leverages Antares' Tjet needle-free injection device to deliver its TEV-TROPIN brand of human growth hormone.

Lastly, shares of Neogen (Nasdaq: NEOG), a company specializing in food and animal testing diagnostics, rose 7% after beating analyst expectations for earnings. Neogen posted earnings per share of $0.28 versus estimates of $0.26, despite falling slightly below forecasts on the revenue line. The earnings upside was partially driven by margin gains from a revenue shift toward higher-margin food-safety diagnostics and the all-important rodenticide, a product I could have used a in a few of my shabby college apartments. If you're as voracious a consumer of both foods and animals as I am, you should be glad companies like Neogen exist.

Foolish bottom line
Despite its defensive label, many individual stocks in the health-care industry are subject to the same daily gyrations you experienced in other industries. Of course, the key to investing successfully is maintaining a long-term horizon. In this special free report on the topic, we outline some of the key savings habits you need to build long-term wealth. We also share three stocks to help build a smarter retirement portfolio. Click here now to claim a free copy.