> But, if a company is paying a 4% dividend, and can borrow at 3.5%, buying back stock reduces the dividend payout, and the company avoids lowering the dividend per share (something that is considered sacrilegious in America).
It's also essentially an arbitrage opportunity at 0.5% gain. The company is borrowing money, buying its own shares, and then using less than 100% of the dividend it would have paid on those shares to pay the interest on the debt, and having the rest left over.
That revenue stream goes away as interest rates rise -- you can't arbitrage 4% ROI against 4.5% borrowing costs -- but it takes time before that has to happen. If the company borrowed by issuing ten year bonds, they're effectively still paying the original (e.g. 3.5%) interest rate until the bonds mature.
At that point they either have to re-borrow the money (which only makes sense if interest rates are still low) or re-issue the shares. But even if they re-issue the shares at that point, they're still better off than having not done it, because they still have the ten years worth of arbitrage profits.
This makes even more sense for the companies that have a pile of cash sitting around making <1% returns, because then the arbitrage profits are even higher (and continue to exist even if interest rates rise more), and they don't even have to pay anything back at the end.