Jack, you are missing the point. Take this  morning for example 92k volume has moved the share price down 5%. It is widely accepted that share buybacks create upward pressure on stocks when the shares are undervalued . That is why big companies often choose to  reward shareholders using buybacks rather than dividends. Buy when the shares are undervalued which supports the share price and sends a clear signal to  shareholders that insiders believe their stock is undervalued.