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The S&P 500 (SNPINDEX:^GSPC) finished at record highs again this week, picking up almost 1% and gaining ground for the third week in a row. But within the S&P 500, Corning (NYSE:GLW), Alexion Pharmaceuticals (NASDAQ:ALXN), and Flowserve (NYSE:FLS) posted double-digit percentage gains on the week. Let's take a closer look at those companies to figure out what made investors so excited about their prospects this week.

Corning gained almost 16% as the company made a big deal with strategic partner Samsung. Before the deal, Corning had a glass-manufacturing joint venture with a Samsung subsidiary in South Korea to help produce liquid-crystal displays for the Asian regional market. Under the terms of the deal, though, Corning will take full control of the joint venture, but in exchange for its share of the venture, Samsung will invest as much as $2.3 billion to take a 7% ownership stake in Corning. The parties both hope that the deal could bolster growth in an industry that has been hurt by consumers moving toward smaller mobile devices and buying fewer large-screen televisions and electronics displays.

Alexion Pharmaceuticals rose more than 15% this week. Most of its gains came Thursday and Friday, with the promising biotech both reporting favorable third-quarter earnings results and announcing that the FDA had given its breakthrough-therapy designation to Alexion's Alxn1101 treatment for a rare genetic disease. Alexion's Soliris treatment saw sales gains of 36% year-over-year even though the drug targets two extremely rare health conditions. CEO Leonard Bell said that the expansion of Soliris to a second indication has pushed sales up at a substantially faster pace, leading investors to gain confidence in Alexion's staying power.

Flowserve also made the top gainers list, with a jump of almost 11%. The maker of pumps, valves, and other equipment to manage the flow of liquids and gases through industrial facilities reported a 19% rise in earnings for the third quarter, with a 5.4% gain in revenue reflecting strength in its oil and gas segment. With so much activity in the energy industry, Flowserve and other ancillary service providers have ridden on the coattails of oil and gas exploration and production companies. As long as oil prices remain high enough to justify unconventional production methods, Flowserve should continue to benefit from the trend.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter: @DanCaplinger. The Motley Fool recommends and owns shares of Corning. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.