Amazon stock up $423 billion in market cap amid longest monthly winning streak since 2011

August is over, and Amazon is (AMZN) ringing in Labor Day weekend with some good news.

The e-commerce company closed out six straight months in the green. That marks Amazon's longest consecutive streak of monthly gains since July 2011.

The stock closed at $138 on Thursday, representing a 3.2% gain for the month of August. The tech giant has gained roughly $423.7 billion in market cap since the beginning of its winning streak.

Thursday's final push came in the aftermath of the company's just-announced Shopify (SHOP) partnership. Amazon announced that its Buy With Prime app will now have an integration with Shopify, making it easier for sellers to connect the Amazon-run payments feature to their Shopify stores.

It's more fuel to the fire of Amazon's investment in Buy With Prime, which is seeing some nice adoption among merchants but is still in its early days.

"Amazon announced in January that it had observed 25% higher conversions on merchant sites in its internal data based on the initial buy with Prime program which began in April of '22," RBC's Brad Erickson wrote on Aug. 31. "Amazon still only has ~60% of its [third-party] sellers using Prime so this is just another way to drive adoption higher over time."

"We do think there has been solid adoption of the existing Buy with Prime program since its full rollout in January," Erickson added, "and there's likely significant crossover between Shopify's [about] 1.75 million merchants and the estimated 2.5 million merchants that sell on Amazon's marketplace — however, still a small tailwind to volume."

The partnership is just another feather in Amazon's cap.

In August, the company reported a series of key earnings beats on operating income, operating margins, and guidance, with the wins temporarily washing away concerns about slowing cloud growth.

"We see 2Q as an inflection quarter for both retail margin and AWS stories and move the name to our favorite idea in Internet," UBS analyst Lloyd Walmsley wrote on Aug. 9.