Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

The Federal Reserve made most investors quite happy on Wednesday, as the perfect combination of tapering quantitative easing while still affirming its commitment to accommodative monetary policy sent most stocks soaring. But despite the big gains marketwide, Jabil Circuit (NYSE:JBL), Onconova Therapeutics (NASDAQ:ONTX), and Gogo (NASDAQ:GOGO) saw their share prices plunge today, with company-specific news sending their stocks down sharply.

Jabil Circuit dropped 21% after its quarterly report left investors uncertain about the electronics-manufacturing company's future prospects. Sales declined but held up better than expected, yet weaker earnings and gloomy guidance for the current quarter disappointed shareholders. Jabil also decided to sell off part of what it apparently considers to be non-core business in its aftermarket-services segment, saying it intends to concentrate on its core manufacturing-solutions capabilities. Even a new stock buyback didn't put much of a dent in the stock's loss, which has already been suffering from major customer BlackBerry's decline.

Onconova Therapeutics declined 19% as the biopharmaceutical company decided to stop its phase 3 trial of its rigosertib drug to treat metastatic pancreatic cancer. Although the combination of rigosertib and Eli Lilly's Gemzar didn't raise any safety concerns, it also didn't appear to enhance survival. With Onconova now having to fall back on other indications for rigosertib as well as other less-advanced experimental drugs in its pipeline, investors are rightfully concerned about the company's long-term prospects.

Gogo fell 16% in the aftermath of private-equity fund Ripplewood Holdings completing its exit of its position in the in-flight wireless service provider's stock. Ripplewood said that it had distributed 27.6 million Gogo shares to its limited partners, raising the possibility that many of them will rush to the exits in order to lock in their paper profits. With Gogo's solid prospects for growth, today's liquidity-based event poses no real fundamental change for Gogo's business, making the drop a potential opportunity for those who believe that Internet access while flying will take off.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter: @DanCaplinger. The Motley Fool has no position in any of the stocks mentioned. 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.