The stock market has been in turmoil recently, but Apple shares have been on a smooth, steady climb. On Monday, the tech giant's stock reached an all-time high of $413.23 before closing at $411.30. The good times continued Tuesday, with the stock hitting $422.86 before closing at $413.45 in a trading frenzy. All this even though the company has made no major product announcements lately, and superstar CEO Steve Jobs stepped down last month. Why the big rally? Here, four theories:

1. iPhone 5 hype
On Monday, a J.P. Morgan analyst predicted that a "significant upgrade" to the iPhone was coming in the U.S. next month, as opposed to the "relatively mild" update — think iPhone 3G to 3GS — many have predicted. He said other markets, like China, would get a minor upgrade geared toward lower-end iPhones. "The implications of this two-pronged launch are meaningful," likely boosting iPhone sales, the analyst said, as quoted at MarketWatch. That optimism might be what pushed Apple stock upward.

2. The iCloud and iOS5
No big announcement seems to be behind the rally, but "signs continue to suggest that Apple is getting closer to rolling out some or all of its iCloud service, as well as releasing iOS 5," says Bryan Chaffin at The Mac Observer. That's my best explanation.

3. It's a rare safe investment
"In uncertain times Apple shares are now considered a 'safe haven,'" says Last quarter, the company's sales were up 82 percent, while earnings-per-share are up 122 percent year-over-year. Investors are optimistic about Q4. Yeah, "forget gold and Treasuries, the safe haven has become Apple," says Fast Money trader Pete Najarian, as quoted at CNBC.

4. The possibility Apple will move to the Dow
"The day could be drawing nearer for Apple's long-awaited ascension to the big time: The Dow Jones Industrial Average," says Jeff Cox at CNBC. Some say Apple's stock rally may be fueled by chatter about Apple finally moving to the Dow — a promotion that would make everybody want a piece of Apple.