Typically it could be a new breakthrough in technology or perhaps an offer to buy the company at a high premium to the current price of the stock..
Many different reasons could cause a spike in the share price. You can look on Yahoo Finance to see the latest news on the particular stock. Be aware that this is a rare event not something that happens frequently.
The markets are really more of an auction, with many parts. If a technology or a buy out is thought to happen simple greed will raise the price. If for example GE hinted that they were going to stop giving dividends a few years ago, and the stock dropped. Then they took back the new and the stock went back to normal. If a company gets a great contract to build a product, the market will reflect the good news. The tech bubble is a perfect example, many of them are not going to be here in 5 years, but the idea of a new Microsoft or a great find drives the market as well. So there are a multitude of answers here, even the weather could affect a stock, like Allstate, if there was a storm and a lot of destruction took place, Allstate may be paying out a lot, and reduce the income. So the value of the company would drop.
I would say the main reason for a large 1 day spike in a price would be the result of a takeover bid. These often are made at a premium of 20% plus.
a lot of different things can do this:
1. the release of financial statements showing really good news (increases revenues/equity from previous year).
2. A press release with good news
3. a press release with very bad news about a main competitor
4. a merging
5. and on and on
Great business ideas, new markets, etc. Apple went up around 14000% over a 10 year period. The funny thing is you know many people sold when they were up 100% and then watched it go up for a decade.
what type of news, and other announcement from a company lead to this kinda of spike
