Programming note: Money Stuff will be off tomorrow, back on Monday.
Look the very standard corporate finance theory is that it’s good for a company if its stock price goes up. A company can issue stock; it can, in a sense, make as much as it wants of its own stock for free. If that stock is worth a lot and keeps going up, it can do things with it. It can sell the stock for money and use the money to do business things. Companies usually pay executives largely in stock, and if a company’s stock keeps going up then it will be able to attract and retain good talented executives because good people will want to be paid in good stock. Employees who own stock will be happy and motivated and will do better work because they keep getting richer. Companies often pay for acquisitions in stock, and, again, having an attractive currency lets a company do attractive acquisitions.