Home Depot Inc. posted stronger-than-expected results for the first quarter, but concerns the breakneck pace of growth could slow once recent stimulus funds dry up has investors on edge.

Same-store sales in the U.S., a key metric in retail, rose 29.9 per cent in the period ending May 2, the company said Tuesday in a statement. That beat the 22.1 per cent average of estimates compiled by Bloomberg. Both customer transactions and average ticket price rose for the quarter, meaning more people placed orders and they spent more every time they did.

Home Depot executives have been hesitant to quantify the impact of stimulus checks on its pandemic results, but executives said Tuesday the latest round of checks “probably” did help drive sales in March and April. Without the benefit of additional stimulus payments and as consumers start to spend more on activities outside of the home, the company will start to “lap very tough comparatives” going forward, said Neil Saunders, managing director of GlobalData.

“For all the positivity, we believe that this quarter represents Home Depot’s zenith, at least in terms of growth,” Saunders said in an emailed note.

The retailer’s shares swung between gains and losses in Tuesday morning trading. Home Depot had increased 20 per cent this year through Monday.

The quarterly sales boom mirrors similar trends at Macy’s Inc. and Walmart Inc., which also posted on Tuesday morning bigger-than-expected gains as Americans get back out to spend. Home Depot executives said on a conference call that DIY customer demand continues to be as high as it was last year, especially in gardening. Interior projects, like counters and cabinets, continued to grow in the first quarter, too.

Nick Shields, a senior analyst at Third Bridge Group, said the sales bump could be from people racing to finish up their home-improvement projects as the pandemic subsides, as well as the boost from stimulus checks.

“Consumers see the end in sight of the pandemic and they want to do all the home improvement while they’re still stuck in home,” Shields said in an interview. That’s driving demand for “all these big-ticket items, like a laundry machine or a new refrigerator.”

Gross profit increased 32.4 per cent in the quarter compared to this time last year. U.S. companies recently have warned about the rising costs of materials, raising the possibility that these prices could be passed on to consumers. The home-improvement market, in particular, has been contending with high lumber prices.

Home Depot didn’t provide any fiscal guidance. In the last quarter it also declined to release a forecast for fiscal 2021, noting continued uncertainty from the COVID-19 pandemic.