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Sitting pretty on Amazon? Don’t be a fool: Gene Munster

Amazon's surprisingly strong earnings report sent its stock zooming Friday, but Piper Jaffray analyst Gene Munster warned that investors shouldn't be complacent.

"Feels like the margins over the next quarters will continue to move higher, but to say we can rest easy for the next few years on that, I would say is a fool's bet," Munster said on CNBC's "Squawk Box." "You never can rest easy on Amazon because … they make such big bets."

Munster added that, during the company conference call, Amazon CFO Thomas Szkutak said e-commerce giant would continue to focus on greater productivity, "which basically means this hope for greater margins continues to be a focus."

In late-morning Friday trading, its share price was up more than 15 percent. (Click here to track the price.)

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On Thursday, Amazon delivered second-quarter results that easily beat Wall Street's expectations. Earnings per share came in at 19 cent a share on revenue of $23.18 billion.

Analysts expected Amazon to report a quarterly loss of 14 cents a share on $22.39 billion in revenue, according to consensus estimates from Thomson Reuters.

Munster said Amazon is taking the right steps in order to do away with the one weapon traditional retailers have had against it: instant gratification.

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"What they've done is ramp up the number of cities with same-day delivery. It's gone up from six to 13. I think that's going to be around 50 cities in the next few years," he said. "Everybody thinks of Amazon as two-day [delivery], that's going to morph into one-day delivery."

AWS a 'key jewel' for Amazon

Neil Doshi, an Internet analyst at Mizuho, said Friday that one of the main components driving Amazon's success last quarter rested on the company's cloud business, Amazon Web Services.

"AWS is one of the key jewels for Amazon. This business itself is on about an $8 billion revenue rate and contributed to over 30 percent of Amazon's total operating income, so [it's] a small piece of Amazon's business, but with very high margins," Doshi said on CNBC's "Squawk on the Street."

He said AWS could be spun off into its own business.

Amazon's pole position with consumers in the retail space is also driving the company's success, said Victor Anthony, an analyst at Axiom Capital Management.

"They have customers locked in right now and the switching costs are high," Anthony told CNBC.