[ergoproxy]

Tim Cook borrows $150B and uses it to buy Apple stock. This shifts the demand curve for Apple stock out (to the right). The equilibrium price of Apple stock rises. Tim Cook sells his stock at the new higher price. He profits.

More likely Joe Schmoe's pension plan will see Apple's stock go up and buy more shares, thinking there's real market demand for it. But there isn't. This is really just a variation on the classic "pump and dump" scheme.

Worst case scenario: Apple does this three or four more times, can't service its debt, and gets driven into bankruptcy. Then Joe Schmoe's Apple shares in his 401k are worth $0.