[bcrescimanno]

Presumably, the stock would be reissued at a point where forces other than supply & demand would have had an impact on the price as well. Yes, the additional available shares on the market would cause a dip--but that dip would not necessarily negate the other effects that (could have) impacted the stock price since the buy-back.

I'm not ignoring the effect; I'm just not viewing it in vacuum.