A buyback is a company spending its own cash to purchase its own shares on the open market, then retiring them rather than reselling them. The mechanical effect is straightforward: fewer shares are outstanding afterward, so the company’s profit is divided among a smaller base, and each remaining share represents a slightly larger slice of the business. A dividend does something related but distinct: it’s “a portion of a company’s profit paid to shareholders,” in investor.gov’s own words, distributed on a schedule or, for a special or extra dividend, at a one-off moment the board chooses. Both return cash to shareholders; a dividend hands it to them directly, a buyback returns it by shrinking the pool everyone’s stake is measured against.
Buying its own stock on the open market would look, in almost any other context, like exactly the kind of trading the SEC’s anti-manipulation rules exist to catch, since a company has information about itself no other trader has and enough capital to move its own price. Rule 10b-18 is the safe harbor that lets a company repurchase shares without that risk, and it does it through four specific conditions, not a general promise of good faith. The company must use a single broker or dealer per day. It can’t buy in the final minutes of the trading session, ten minutes for the most heavily traded stocks, thirty for everything else, and it can’t be the trade that opens the day. Its purchase price can’t exceed the highest independent bid or the last independent trade price, whichever is higher. And its daily buying can’t exceed 25% of the stock’s average daily trading volume, a limit meant to keep a company from becoming its own biggest buyer on a given day. A company that stays inside all four conditions gets the safe harbor; a company that steps outside them is repurchasing shares at its own legal risk.
Since January 1, 2023, buybacks also carry a direct federal cost that dividends don’t. Under section 4501 of the tax code, added by the Inflation Reduction Act, a covered corporation owes a nondeductible excise tax equal to 1% of the fair market value of stock it repurchases during the year, net of stock the company issues over the same period. It applies specifically to publicly traded corporations repurchasing their own stock, and it took effect for repurchases made after December 31, 2022. The tax doesn’t ban buybacks or cap their size; it puts a small, fixed cost on the dollar amount repurchased, payable regardless of whether the buyback was funded from cash on hand, debt, or anything else.
Why a company chooses a buyback over a dividend, or over paying down debt, or over investing in the business, usually comes down to flexibility and to what a buyback offsets. A dividend is a standing commitment investors come to expect and punish a cut to; a buyback can be started, paused, or stopped without that same signal. Buybacks are also the main tool companies use to offset dilution from stock-based pay: a company that grants a meaningful number of shares to employees each year, through options or restricted stock units, sees its share count creep up every year those grants vest, and repurchasing a matching or larger number of shares keeps the total outstanding roughly flat, or lower, despite the new grants. Read alongside a company’s stock-based compensation expense, the size of its buyback program is a reasonable answer to a specific question: is this company returning cash to existing shareholders, or mostly using its buybacks to cancel out the new shares its own pay programs keep creating.