When people think of Walmart, one word usually springs to mind: growth. It is after all the world’s largest retailer, having risen from a single store in Arkansas, to a global business in 27 countries with sales in excess of $440bn.

Yet, despite its many achievements, it has recently been dealt a reality check, particularly in its core US market where it has recognised that top-line growth is no longer a given.

Over the past 50 years, it has succeeded by following a very simple model: low prices, a wide range and a one-stop shop. The problem is today there is another more relevant channel vastly encroaching on its turf and invalidating its model - the internet.

Amazon is Walmart’s biggest threat, leaving it scrambling to make up lost ground so it can compete in an increasingly digital world. And Walmart is not alone. Tesco and Carrefour’s recent woes in their domestic markets show how the big-box model is running out of steam.

In our book, we estimate Walmart will by 2020 reach saturation with the US Supercenter format that has fuelled expansion at home over the past couple of decades. Now it is proactively exploring new avenues for growth in e-commerce but small-box retailing and further international expansion as well.

In the United States, the Walmart Express format is enabling it to gain access to previously underpenetrated urban areas. This is Walmart’s last opportunity to expand in a meaningful way in its core market, yet it’s also a means of fending off those pesky dollar stores that have been eating Walmart’s lunch.

Drugstores are also increasingly a thorn in its side, as they beef up their food and enhance own labels. With three-quarters of the US population living within five miles of a Walgreens, it’s no wonder Walmart has finally made a move for small-box.

But it’s not just the US operation that is downsizing. Proximity formats are a key theme globally, with much inspiration being drawn from the retailer’s bodega formats in Latin America.

Walmart is also increasingly sharing knowledge across its global estate and finding new, innovative ways to achieve efficiencies, particularly in sourcing. IPL, for example, the South Africa-based Asda subsidiary, now not only supplies fruit and groceries to the UK but other Walmart markets as well. Meanwhile, George clothing is sold in Walmarts across seven countries, and will penetrate an entirely new region this year when it opens in the Middle East.

Walmart should not, however, move too far from its core model. Low prices and a wide assortment have become prerequisites for many shoppers, and Walmart fails when it veers too far from its core. During the recession, shifting away from EDLP and rationalising its SKU base led to nine consecutive quarters of declining comparable store sales.

Since adding back 9,000 products and restoring low prices, both sales and traffic have improved, a sign that, while we question the longevity of the formula, back to basics can still be a winner.