One of McDonald's (NYSE:MCD) core menu staples, the Big Mac, is turning 50 years old in 2018. And decades after the product's introduction to the menu in 1975, the fast-food titan still sells millions of Egg McMuffin sandwiches. These days, though, many of those breakfast meals are being consumed in the afternoon or evening hours.

That popular menu continuity has supported an incredible streak of steady returns for Mickey D's shareholders. Its dividend, for example, has increased in each of the last 43 years.

But lots has changed about the business -- especially in just the past few years. Let's take a look at two of the shifts that have made the most difference for investors.

Back in the leadership spot

Following a brutal stretch of market share losses, McDonald's has now recaptured its leadership position in the industry. Sales at existing locations, or comparable-store sales (comps), improved by 5% in 2017 after declining in each of the prior four years. Comps rose 5.5% in the most recent quarter to mark Mickey D's 11th straight quarter of positive results and its fifth consecutive quarter of increased customer traffic.

That traffic trend has been the key driver of improved market share results. Guest counts recently returned to positive territory after sinking in each of the prior four years.

Chart showing improving traffic trends in each of the last three years.

Data source: McDonald's financial filings. Customer traffic change by fiscal year. Chart by author.

Global and U.S.-focused peers are all struggling to keep up with the burger giant. Yum! Brands reported just a 1% comps improvement to start 2018. Starbucks' pace was 2%, and Dunkin' Brands posted a slight decline. Better burger specialist Shake Shack, meanwhile, saw its sales shrink at existing locations this past quarter.

Heavily franchised

Back in 2013, McDonald's owned and operated roughly 20% of its 34,000 global locations. That proportion of company ownership has plummeted since then, though, to hit 8% in the most recent quarter.

Many of its peers are also pursuing refranchising strategies or are almost 100% franchised already. However, McDonald's is seeing a greater financial benefit to this shift since its rent, royalties, and franchise fees are generally higher.

As a result, its profitability has soared in the past few years and now trounces its rivals by an even greater margin.

MCD Operating Margin (TTM) Chart

MCD Operating Margin (TTM) data by YCharts.

More changes to come

Investors can expect more financial benefits ahead as the restaurant chain moves toward its long-term goal of owning just 5% of its restaurant base. In fact, CEO Steve Easterbrook and his team are targeting operating margin in the mid-40% range by 2019.

Looking further out, the next few years are likely to bring big changes to the ways a typical McDonald's store looks and operates.

Friends sharing a fast food meal.

Image source: Getty Images.

Executives are pouring $2.4 billion into restaurant remodels and upgrades in 2018 to mark a 20% increase from the prior year. The new designs should speed up the ordering experience through technology like kiosks and digital ordering options. They'll pave the way for limited-time menu introductions, too, but McDonald's is determined to rely on its iconic food items as its core growth avenue.

These capital investments will leave less room for McDonald's to spend tons of cash buying back its own stock as it has in the past few years. But, the difference these days is that the restaurant chain has positive momentum on both the top and bottom lines, and management is determined to do what it can to keep the good times rolling.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.