These 3 Stocks Have Bought Back Billions, But Which Offers the Best Value?

Key Points

• AutoZone's buybacks have supported earnings-per-share growth, but the price paid for repurchased shares remains important.
• Marathon Petroleum announced another $5 billion repurchase authorization, supported by strong refining earnings and MPLX distributions.
• Corpay continues to repurchase shares while growing revenue, although debt and valuation remain considerations.

Share repurchases often go unnoticed, but some companies engage so aggressively in buybacks that they become a core part of their earnings growth strategy. AutoZone Inc. NYSE: AZO, Marathon Petroleum Corp. NYSE: MPC, and Corpay Inc. NYSE: CPAY have each repurchased a substantial portion of their outstanding shares in recent quarters, retiring 20% or more over about five years. With recent earnings reports, two of these firms just announced new buyback activity as well.

For each of these companies, investors must assess whether their share buybacks are effectively creating shareholder value by improving earnings per share (EPS) performance or other means. Aggressive buybacks do not necessarily make a stock a good investment, particularly if they are funded with debt or if the company is stuck at an elevated valuation.

AutoZone's Buyback Machine Is in High Gear, But So Is Valuation

AutoZone has a long history of repurchasing shares, including in its most recent quarter. Over five fiscal years, weighted-average diluted shares outstanding have fallen by about 26%, including about $2 billion spent on shares in fiscal 2026. At the same time, AutoZone's net income has grown more modestly, while its free cash flow generation has remained robust, allowing it to continue funding additional buyback authorizations over time.

For investors, it's important to keep in mind that much of AutoZone's headline-grabbing per-share growth can be attributed to a lower total share count rather than organic growth. This is reflected, for instance, in the firm's 6% year-over-year (YOY) revenue growth that still came in more than $107 million below analyst predictions.

So long as AutoZone buys back its shares at a reasonable price and its defensive business continues to generate healthy cash flows, there may not be anything inherently concerning about this approach. However, with a price-to-earnings (P/E) ratio of about 21, AZO shares are not especially cheap, even though that valuation is below some recent peaks.

That is, AutoZone is getting fewer shares for each dollar it spends in buybacks now, which reduces the potential benefit to EPS.

Marathon's Massive Buyback Program Is Getting Bigger, and the Firm Can Fall Back on Other Resources If Refining Cycle Slows

In the latest quarter, Marathon returned $3.3 billion to shareholders, about 90% of which was the result of share buybacks. This continues a trend established with the sale of Speedway in 2021 that has seen the firm reduce its overall share count by about half in just five years. Additionally, Marathon just announced another $5 billion repurchase authorization.

With such an aggressive buyback program, investors may understandably be skeptical of Marathon's capacity to maintain momentum. This is especially important to consider when refining stocks, and oil and gas names more broadly, have been rapidly appreciating amid energy sector turbulence.

Still, despite returning about 148% year-to-date (YTD), MPC shares have recently dipped, falling by more than 11% in the last month. This is a reminder of the cyclical nature of refining earnings.

Two key factors could help to sustain Marathon's repurchase momentum even in a less supportive environment. First, it receives billions annually in distributions from its midstream energy partnership, MPLX LP NYSE: MPLX, helping to cover its dividends and a substantial portion of capital spending without even including refining earnings. Second, management has maintained substantial liquidity, which may suggest a prudent approach in case capital becomes scarce.

With a P/E ratio of about 14, Marathon's recent pullback may present the greatest buying opportunity among the three companies on this list.

Corpay May Be Overextended

Global payments firm Corpay achieved strong adjusted EPS growth as well as aggressive repurchases in its last earnings report, on top of 18% YOY revenue gains, with wins on both the top and bottom lines.

Buybacks are likely adding several percentage points to per-share growth, but not enough to fully drive the firm's earnings performance. Corpay may be better able to rely on its core business performance to fuel growth than AutoZone, for instance.

Still, Corpay's debt load is not insignificant either, and the company has continued to fund acquisitions as well as buybacks while taking on additional debt. While buybacks financed in this way can be risky, so long as Corpay maintains strong cash flow, investors may find them sustainable. At the same time, with CPAY shares trading at roughly 25x earnings, the stock is not especially cheap, particularly compared with Marathon. Despite returning about 54% YTD, CPAY shares may struggle to maintain momentum for this reason.