$GE Aerospace (GE.US)$ Stock buy backs can be good for intrinsic value but it can also be bad for intrinsic value. If the money spent is done at a price that is substantially above the companies present intrinsic value then it probably just wastes cash. Especially if the company borrows money to buy back shares.
I think GE is a good example. They wasted billions in share buybacks meanwhile their core buisness declined. The share buybacks didn't mean much because retained earnings fell and the companies balance sheet became a mess.
The worst is when a company does stock buy backs and the buisness has a major problem thus they are forced to sell shares below the stock buy back price. Basically a lose lose for everyone involved.