Cash has nothing to do with market cap, except that it has everything to do with company valuation, at least when it's done by rational people. And that affects stock prices.
You must mean unknowledgeable people.
The most important single thing to understand is that material assets do not belong to the stockholders of a public company. Equity is what they own. The cash and other assets accumulated by the company (as represented by book value) are only of interest to investors if the company should (1) be taken over in its entirety by someone else, or (2) the company is liquidated in bankruptcy. In the first case, the cash and other assets are now owned by the buyer, as they now own the company lock, stock and barrel; so, the book value might have an impact on the takeover price. In the second case, some of the assets of the company might be used to pay off stockholders, but only rarely. Bankruptcy is designed to make creditors whole, and since stockholders are not creditors, they typically get nothing in a bankruptcy.
So, do you think either case (1) or case (2) are likely for Apple? Of course not. Consequently cash is an intangible asset as far as investors are concerned, unless the company decides to pay a dividend or buy back shares. Both of which Apple is presently doing.
As I said above, an explanation requires an understanding of earnings and multiples, since this is how stocks are valued. Equity investors are interested in earnings per share (EPS). If a company with a million shares outstanding earns $10 million, then EPS is $10.00. If the price to earnings ratio (PE) for the stock is 10, then the stock will trade at $100.00. If with the same earnings, the company buys back half of their shares, then EPS will be $20.00. Holding the PE constant at 10 (and there's no reason why it should change in this scenario), then the shares would trade at $200.00, each share now representing twice as much of the company's earnings as before the buyback.
This is why stockholders like buybacks. It is not a zero-sum game.
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How much of that market cap is there just because Apple does have those massive cash-reserves ?
None. See above.
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Yes and no, most analysts are prevented for buying and selling the securities they are monitoring. During black-out periods, which the financial institutions have just before and just after issuing an analyst-report.
This is for brokers, prop-traders at banks and some other people.
A private investor like Mr. Ichan is only obliged to not lie about what he is doing on order to move the stock in any direction. What he is doing now is not illegal. I do agree with him, but not on the magnitude. The buy-back should be 50-100B.
To not deliberately mislead. Call it lie, if you must. If they trade on the misleading or false information, then the SEC will come knocking. They also know about proxies and those sorts of dodges.
You may recall the false alarm about Steve's death that we went through a few years back. Some news service even ran an obit. Steve was very much alive at that point, but the stock tumbled just the same. Investors made and lost money that day. Was anyone prosecuted for the story? As I recall, it was investigated by the SEC but in the end judged to be a honest mistake. So it wasn't a violation.