Buying back stock is one of those nearly surefire ways companies can help their shareholders. With stock buybacks, a company can reduce the total shares outstanding, leaving stockholders with a greater claim on a company's earnings.

For example, let's assume a company earns $100 and has 100 shares. That works out to $1.00 in earnings per share. But if the company buys back 25 shares, each share now represents $1.33 in earnings. Over the long run, growing companies with consistent buyback programs tend to deliver attractive investor returns.

Here are three companies doing just that today, and they are worth a closer look.

Autozone

Since the turn of the century, the nation's leading automotive parts and accessories retailer, Autozone (AZO 3.74%), has had one of the most impressive share repurchase programs around. 

AZO Shares Outstanding Chart

AZO Shares Outstanding data by YCharts.

Autozone, which operates roughly 7,000 stores across the U.S., Mexico, and Brazil, sells a wide variety of automotive products ranging from critical parts like batteries and fuel pumps to discretionary items like air fresheners.

While this business model might sound relatively simple, the consistent growth in the number of vehicles on the road as well as a higher average age of those vehicles has led to steady growth in serviceable customers for Autozone. This has helped the company grow its same-store sales by roughly 4% a year for more than a decade. 

Additionally, thanks to Autozone's scale, the company has been getting better and better rates from suppliers, leading to an expansion in its profit margins and market share gains against its smaller competitors. This combination of industry tailwinds and competitive advantages has helped Autozone deliver a nearly tenfold increase in net income since 2000.

Though that's pretty impressive growth on its own, thanks to the buyback program, its earnings per share have increased roughly 72-fold during that same time period! 

With Autozone's stock trading at a price-to-earnings ratio of roughly 20 -- slightly above its five-year average -- it seems shareholders can continue to expect strong returns. 

Lowe's

Like Autozone, Lowe's Companies (LOW 1.24%) is a leading retailer in a massive industry, only instead of cars, it's homes. Lowe's is one of the two major home improvement chains in the U.S., along with Home Depot, and both companies have been gaining market share from their mom-and-pop counterparts thanks in part to their ability to get better prices from vendors.

Similar to the automotive market, the home improvement category has seen consistent growth over the last several decades thanks to a steadily increasing number of housing units as well as the aging of existing housing stock. With more new homes and older homes each year, Lowe's has been right there to provide the lumber, appliances, and any other home improvement products its customers might need.

In fact, it has grown its overall revenue by about 6% annually over the last decade despite actually decreasing its total number of stores. This focus on optimizing its footprint has led to improved sales per square foot and higher profit margins across the company, resulting in roughly 11% annualized earnings growth over the last decade.

But it doesn't stop there. Management also reduced its total shares outstanding by 44% during that period, helping to supercharge the company's earnings per share. 

LOW Net Income (TTM) Chart

LOW Net Income (TTM) data by YCharts.

With Lowe's trading at an earnings multiple below its historical average and its competitive advantages still very much intact, investors willing to hold for the long term should be well-rewarded for owning shares here. 

Sprouts Farmers Market

Sprouts Farmers Market (SFM -0.44%) is a specialty grocery chain with locations concentrated in the Southeast and Southwest.

However, unlike chains such as Kroger and Walmart, Sprouts operates out of smaller stores -- 23,000 square feet to 30,000 square feet in size -- and focuses on supplying unique, local products, particularly for customers with dietary restrictions such as dairy-free, gluten-free, vegan, etc. In fact, these "attribute-based" items (as management refers to them) account for 70% of what the company sells. 

With this focus on specialty products, Sprouts is able to generate gross profit margins above 30% -- significantly higher than most grocery chains. Over the years, these superior margins have helped the company generate strong free cash flow that management has been using in part to steadily repurchase its own shares. Since the start of 2016, Sprouts has reduced its shares outstanding by just over 5% a year. 

SFM Free Cash Flow Chart

SFM Free Cash Flow data by YCharts.

Sprouts, though, is a much less mature business than Lowe's or Autozone, and after recently adding several new distribution centers, the company looks set to expand its store count at a much quicker rate. "We should be looking at 10% net (store) growth from 2024 and beyond," said CEO Jack Sinclair during the company's earnings call on Aug. 1.

While this expansion might require pouring more of its profits into building new stores and deploying less to stock buybacks for the time being, that seems like the right strategy for this small but successful chain. Considering management's stellar track record and the fact that it's trading at just 15 times free cash flow, Sprouts strikes me as a stock worth buying now and holding for the long haul.