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Walmart $WMT -2.50% reported first-quarter revenue of $177.8 billion on Thursday, a 7.3% increase from a year earlier, as gains in e-commerce and higher-income shoppers helped drive comparable U.S. store sales up 4.1%, excluding fuel. That beat analyst expectations of $174.98 billion in revenue and comparable sales growth of 3.85%, according to CNBC.

On the bottom line, adjusted earnings per share of $0.66 were in line with what analysts had penciled in, according to CNBC. Net income for the quarter reached $5.33 billion, an 18.8% year-over-year improvement. Across Walmart's global business, e-commerce volume expanded 26% and the advertising segment posted 37% growth.

Despite the top-line strength, higher fuel prices emerged as a pressure point on margins. Operating income was negatively affected by 250 basis points from elevated fuel costs in distribution and fulfillment, the company said. Speaking with Bloomberg, CFO John David Rainey indicated that the company took on nearly all of the quarter's fuel cost increases itself — a headwind of around $175 million — and warned that a similar or steeper burden could materialize in the months ahead.

"It'll probably be larger than that in the second quarter if fuel prices stay where they are, so we're absorbing those prices and still maintaining our guidance, and I feel really good about that," John David Rainey told CNBC.