I disagree, the promise was to give them a return on their initial investment, with the shareholders assuming the risks that a profit might not ever be generated or that the rate may be below their liking. Generalizing that to 'work in the shareholders interest' is too much. They retain the same rights, whenever they entered the market. They can exercise a vote at a shareholders meeting, or they can sell their share at a profit or loss. Their is no guarantee that all future derivative sales will be at a profit to the speculator. It is ridiculous to assume it would be, since it is fundamentally out of control of the issuer.
You have the right to resale, of course, if you think the stock is overvalued for your potential returns, you can always sell it.
I mean, think about an extreme case. The equity could be involved in a speculative bubble and could rise in value to obscene amounts. How could the corporation in that case be obligated to act in the shareholders interest? They can't control speculators and they can't guarantee profits to people speculating on paper they sold decades ago. It's _your speculation_, so it's _your risk_. At this point your profit should not be a concern to them, imo.
If indeed, they ever fell on low times, then the situation would change. If they needed to borrow against their market cap, or needed to do another offering. But that is not the case, is it?
The opportunity for a shareholder to sell stock to a another potential shareholder at a profit is not in any way relevant to a corporation seeking to maximize shareholder value and return on investment. We all know speculation happens but that's not what I'm talking about here. It's the responsibility of the corporation to provide a return on investment to whoever is holding the shares right now. That means increasing earnings, or paying out a dividend. Should the price of a stock go up because earnings per share have gone up, that's a happy side effect for shareholders but irrelevant to Apple's responsibilities.
One such method of increasing earnings per share is to spend cash reserves to grow the business. Apple is doing that, but the cash reserves are growing faster than Apple can spend to grow. So Apple started giving out a dividend, and there's talk of increasing earnings per share by reducing the number of shares in the wild. Apple claims they are already doing everything with their cash that they can to grow the business. Since there's money left over, they have a responsibility to provide a return. They're not a depository, they're a business.