Everyone who worked in the PC division of IBM essentially worked for Lenovo one day. They used the same people, processes, part numbers, etc for many years. Lexmark was the same story a few years earlier.
The only change was that the IBM account exec that plays golf with your CEO didn't give as shit about PCs anymore.
In order for a business to invest that "cash" in their own business, it needs to be a better investment than whatever else it had been invested in.
The common complaint about apple is that they're not expanding/diversifying their business more with their available capital.
Not that they're doing nothing with a literal pile of cash.
This return rate is termed "opportunity cost", i.e. if Apple were to invest it in Apple's business it needs to return a higher rate than the opportunity cost.
http://en.wikipedia.org/wiki/Cash_and_cash_equivalents
which include "equities" which include common stocks:
http://en.wikipedia.org/wiki/Security_(finance)
So, it may very well and likely is invested in stocks. It is hardly sitting idle.
"Marketable securities" is an extremely broad category. Some marketable securities are cash equivalents, but common stocks are not. Their value is too volatile to be considered a cash equivalent.
To qualify as a cash equivalent, an asset must have very little chance of decreasing in value. Such assets tend to have very low return on investment.
I find it extremely improbable that a sophisticated company like Apple would let $13 billion sit around in an unproductive investment. If you can quote an accounting rule that says "cash equivalents" cannot be common stock, I'd like to see it.
> Another important condition a cash equivalent needs to satisfy is that the investment should have insignificant risk of change in value; thus, common stock cannot be considered a cash equivalent
In any case, preferred stock is listed, which are productive investments.