Explanation:

A buyback, also known as a share repurchase, is when a company buys its own outstanding shares to reduce the number of shares available on the open market. Companies buy back shares for a number of reasons, such as to increase the value of remaining shares available by reducing the supply or to prevent other shareholders from taking a controlling stake.
A buyback allows companies to invest in themselves. Reducing the number of shares outstanding on the market increases the proportion of shares owned by investors. A company may feel its shares are undervalued and do a buyback to provide investors with a return. And because the company is bullish on its current operations, a buyback also boosts the proportion of earnings that a share is allocated. This will raise the stock price if the same price-to-earnings (P/E) ratio is maintained.