Stock buybacks are when companies buy back their own stock, removing it from the marketplace. Stock buybacks increase the value of the remaining shares because there is now less common stock outstanding and company earnings are split among fewer shares.
Buybacks are sometimes an indication that a company perceives their stock to be undervalued, but it is up to the investor to determine if the company is correct. Companies that are favorable to shareholders may often issue dividends and perform stock buybacks.
Total Value of Shares Repurchased from the Marketplace.
YCharts uses "Net Total Equity Issued" from the statement of cash flows to approximate stock buybacks (multiplying by -1 since this number is negative in the case of a buyback). Hence, it includes the buyback of both common and preferred shares.