I wouldn't even say they defer them, because the taxable event has not occurred. It allows people too let leave their money at risk longer, including the gains.

I wouldn't even say they defer them, because the taxable event has not occurred. It allows people too let leave their money at risk longer, including the gains. If BuyBacks make stock price go up, stockholders haven't made any money yet. They can be wiped out at any time and lose everything. BuyBacks simply give the shareholders the choice of if and when to cash out any gains and losses they may have.