Businesses Prodded to Reveal More Expense Details to Investors

Walmart Inc.'s financial reports list expenses of hundreds-of-billions-of-dollars in two broad categories, leaving investors to hunt elsewhere for everything from the wages paid to employ its army of associates, to the mammoth quarterly costs of freight and fuel.

The world’s largest brick-and-mortar retailer is hardly an outlier: More than a quarter of the S&P 500’s top 100 businesses group all their expenses into three or fewer line items, with a single broad expense bucket—like “administrative costs"—covering everything from payroll to supplier costs to advertising. And almost half of the top 100 companies mash all their expenses into four or fewer ...