It's actually Float Shares * Market Price.
This doesn't make much of a difference in Apple's case, because most of their market share is floating on the public market. Quick calculations:
932.37M Shares Outstanding x ~$600/share = $559.4B Mkt Cap
931.79M Float Shares x ~$600/share = $559.0B Price to go Private
$400mm, in this case, doesn't make much of a difference, but if you talk about this for other companies in the future, keep it in mind.
You're clearly alluding to Facebook being "forced" to go public, but they too could remain private with 501 investors. But once they're revealing their numbers, they figured they might as well jump in with both feet and do the IPO.
if (NumOwners >= 500) public = true;
Different than being a publicly traded company.
If Apple consumes about $15 billion a year in cash for its stock buybacks and dividends, it is generating so much new cash from its business that its total cash balance at the end of fiscal 2013 could be around $180 billion, estimated Gene Munster, an analyst at Piper Jaffray.
http://www.nytimes.com/2012/03/20/technology/apple-to-use-ca...
Market cap != Value assets
The 550B market cap is the value of all outstanding shares of the company which is not equal to value of the combined assets like buildings and $$.
For more information, you could look at Benjamin Graham's "The Intelligent Investor". This is a very good introduction to investment, but it's also quite a long read.
Source: http://www.businessweek.com/1997/34/roster34/aapl.htm
this is exactly what they're trying to signal because its true. what's wrong with that? they've been extremely profitable while not spending the $45 billion they're giving back to shareholders, and they can continue to be profitable without it.
> In reality Apple could probably just become a private company by buying back most/all the public shares
no it couldn't. it's market cap is 550B. it's cash reserve is 100B.
more generally, a company cannot buy itself because the shareholders actually own the cash the company holds. generally, if a company has $X dollars of cash reserves, then the market cap on that company would be > $X.
edit: a factor of 10