Has Wal-Mart hit its ceiling?

Not every milestone worth celebrating.

For the first time ever — or at least since the company went public some 45 years ago — Wal-Mart Stores Inc.’s revenue shrank from the year before, according to its annual financial filing released this past week.

Wal-Mart is clearly having trouble adapting its gigantic stores to the Internet age.

To be sure, it is a retail juggernaut that brings in half a trillion dollars. Still, WalMart might have just hit its growth limit.

And the sales dip comes despite the fact that Wal-Mart spent $11.5 billion (roughly matching what J.C. Penney made in sales last year) to build more than 400 new stores, remodel old locations, and revamp its website and other technology to better serve its customers.

Though Wal-Mart shares were a safe haven in the rocky start of 2016, investors are pricing in more weakness. The stock has fallen behind retail competitors and the broader market.

In February, Wal-Mart lowered its annual net sales

is growth forecast to “relatively flat,” from earlier guidance that called for an increase of as much as 4% (the company has pointed out that previous guidance didn’t account for currency changes, which have stung the global retailer).

Wednesday’s filing attributes part of the 2015 sales drop to currency impacts and a decrease in fuel sales due to lower gas prices. Sales have also suffered from ongoing store closures, including the shuttering of its entire fleet of smaller “Express” stores.

ButWal-Mart also acknowledged it has shifted the way it runs the company, dropping a long-time focus on growing net sales and cutting operating expenses as a percentage of sales. Its aim now is on making “strategic investments” to support the “long-term health of the company.”

While that’s happening, Wal-Mart warned, it may not be able to deliver the kind of steady net sales and profit growth investors have grown accustomed to seeing. (It notes, though, that it will continue to build new stores and e-commerce capabilities and grow sales at established stores.)

While jarring, these changes aren’t necessarily bad. WalMart remains a massive retail force, and investors shouldn’t discount the muscle behind any decision it makes. This can already be seen in its fastgrowing mobile app and its rapidly expanding and seemingly successful grocery pickup program, which lets shoppers order groceries online and then swing through a Wal-Mart drive-through to pick them up.

It’s also pretty amazing that executives are finally willing to take poor results on the chin and veer away from precedent in order to morph the company from a mostly brickand-mortar operation into one that serves customers the way they want to shop — whether in stores, the web, on mobile or a mix of all three. And if these investments work, they could position the company for another halfcentury of retail dominance.

But what Wal-Mart doesn’t have is an unlimited amount of time. Reporting declining sales might be OK for a year or two, but at some point a turnaround plan could become a failed strategy. Its first revenue decline should serve as a wake-up call.