Walmart is rolling out an unlimited shipping service that could undercut Amazon Prime.

Walmart said it will offer a subscription delivery service this summer for $50 a year, roughly half the price of Amazon Prime, with its annual fee of $99.

The discount chain said the products would arrive within three days.

Walmart currently has an online ordering system that offers free shipping for orders that are $50 or more. Amazon has a better deal, with free shipping on orders over $35.

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