Wednesday brought huge amounts of volatility to the stock market, as initial gains gave way to losses briefly this morning after Federal Reserve Chair Janet Yellen discussed potential economic risks that could endanger the U.S. economic recovery. But news that Russia had taken troops off the Ukraine border pushed most stocks higher, and J.C. Penney (NYSE:JCP), Mondelez International (NASDAQ:MDLZ), and Activision Blizzard (NASDAQ:ATVI) were among the best-performing stocks in the market today.

Source: J.C. Penney.

J.C. Penney climbed almost 8% as the struggling retailer got an analyst upgrade. It's hard to feel all that confident about an upgrade from sell to neutral, but the thesis behind the upgrade is generally that, given the horrible year that J.C. Penney had in 2013, even tepid 2014 results will look reasonably good by comparison. The resulting upward bias for same-store sales growth could well make casual investors believe that J.C. Penney has fully recovered, bolstering the stock and creating upward momentum. In the long run, J.C. Penney still faces a huge task in trying to regain all the customers it lost during the past several years. For now, though, even minor progress is worth celebrating.

Mondelez International rose more than 8% as the global-foods giant announced that it would contribute its coffee business to a joint venture with a major European coffee company in exchange for $5 billion in cash and a minority 49% stake in the combined company. The news was positive enough to overcome earnings and revenue projections in the Mondelez quarterly report, but Mondelez also said that it would go through corporate restructuring to cut costs by as much as $1.5 billion within the next four years. As competition in the food industry becomes fiercer, Mondelez needs to explore innovative ways like this to cement its place among the top food companies in the world.

Source: Activision.

Activision Blizzard picked up almost 9% after its quarterly report surpassed investors' expectations. Adjusted revenue dropped 23% from the year-ago quarter, but even so, Activision Blizzard still topped its own previous guidance, and growth in Europe and the Asia-Pacific region helped to offset a nearly 19% drop in North American sales. Activision Blizzard is spending more money on product development, and that has hurt margins. But it also puts the video game company in a better position to capitalize on changing trends if it can come up with the next blockbuster video game series to follow its hugely popular World of Warcraft and Call of Duty franchises.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool recommends Activision Blizzard. The Motley Fool owns shares of Activision Blizzard. Try any of our Foolish newsletter services free for 30 days. We Fools may not 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.