BENTONVILLE, United States — Wal-Mart Stores Inc.'s ShippingPass e-commerce subscription program will begin offering delivery in two days rather than three, escalating competition with Amazon.com Inc.'s Prime.The retailer also is cutting the price of the program by $1 to $49 a year, according to a statement on Thursday. Amazon’s Prime costs $99 annually, though it also offers other perks such as free movies and TV shows.ShippingPass, still in a pilot phase, lets Walmart.com customers get free delivery of more than 1 million products on the site. The idea is to encourage frequent shopping and lock in customers — something Amazon’s Prime has achieved with its tens of millions of members. Despite being the world’s largest brick-and-mortar retailer, Wal-Mart is still struggling to catch-up to Amazon online.Wal-Mart’s strategy in e-commerce is to rely on its stores and distribution centers to support its online efforts. Over the holiday season, the company encouraged shoppers to place orders on its website and pick the products up in stores.With ShippingPass, Wal-Mart’s existing infrastructure is helping it lower delivery costs, the Bentonville, Arkansas-based company said on Thursday.“We can offer faster and more affordable shipping because we have a unique fulfilment network that includes new large scale fulfilment centers, stores, distribution centers and our transportation network,” Wal-Mart said in the statement.By Shannon Pettypiece; editors: Nick Turner and Kevin Orland.