Walmart Inc. is big in almost every way — 4,755 stores, 1.5 million employees and $380 billion in revenue in the United States alone. But one part of the world’s largest retailer remains minuscule. “We have a tiny ad business,” CEO Doug McMillon told investors in October. “It could be bigger.”

Walmart Inc. is making sweeping changes to its employment policies this month, granting paid sick leave to hourly workers in the United States, and, at the same time, possibly making it easier to fire those who miss too many shifts.

Amazon.com and Target Corp. have opened the floodgates on free shipping. Recent moves by the retailers to eliminate minimum-purchase amounts for free shipping have boosted the share of online orders that get delivered gratis, according to data from retail analytics company DynamicAction.

Look out, Amazon: Walmart is coming to steal your lunch — and maybe dinner too. The world’s largest retailer has surpassed the e-commerce giant in a survey of online food shoppers, more of whom said they most recently visited Walmart’s site for groceries.

Target Corp. is expanding perks like free two-day delivery to snag as much as possible of the $100 billion in sales the company sees up for grabs from retailers that have gone under.

Walmart Inc. is building a high-speed grocery warehouse to solidify its position as the nation’s biggest grocer.

Walmart Inc. has refurbished its Jet.com site to cater even more to the city dwellers who make up the bulk of its shoppers.

Walmart Inc., pinched by the worsening shortage of truckers, plans to double its spending on attracting and retaining drivers by year-end.

Walmart Inc. bounced back from a lackluster start to the year with the strongest sales gain in more than a decade fueled by its grocery business, brightening the outlook for the overall retail sector. The stock jumped as much as 11%, the most intraday since October 2008.

Walmart Inc. has relaxed deadlines for some supplier deliveries just months after tightening them, easing pressure on manufacturers who are grappling with a driver shortage.