At their worst, stock buybacks can be a form of corporate cannibalism. Often the unspoken motive is to use extra cash to boost earnings per share by reducing the number of shares among which the company's profits are divided. But that can be a slippery slope says Kevin Beech, an Analyst at Behind The Numbers. "If they don't keep repurchasing stock, their earnings will take a hit. So it can turn into a sort of an addiction."
Another question is how prudent will they be in their repurchase? Will they do so at a high p/e (flashback to NFLX Reed Hastings buying back @ $300/share in 2011) or will they do so on weakness and during dips?
Still others actually target names with a share repurchase as short candidates for a variety of (very possibly prudent) reasons. (Hat tip to veteran member GT)
Lastly you must ask yourself do companies with stock buybacks perform as well, better or worse than the S&P? Talking heads would have you believe a stock repurchase drives prices higher........