NEW YORK — Amazon.com Inc. has scheduled its second annual Prime Day — the online retailer’s version of Black Friday for its Prime members — for July 12. The one-day promotional event, offering numerous discounts, is exclusively for members of the Amazon Prime loyalty program.

According to the company, the first Prime Day, which occurred last July 15, was the biggest single shopping day in Amazon’s history. Amazon said it sold 34.4 million items, more than its highest Black Friday volume, and signed up hundreds of thousands of new Prime members.

Amazon does not reveal its actual Prime membership totals, but some analysts estimate the number at somewhere between 58 million and 70 million ­worldwide.

This year Walmart made a major move to pre-empt Amazon’s Prime Day, recently offering a 30-day trial membership of its ShippingPass program, which, like Amazon Prime, provides free two-day shipping with no minimums. The annual fee for ShippingPass is $49, compared with Amazon Prime’s price tag of $99 a year.

ShippingPass was initially launched last summer but offered three-day delivery within a limited array of markets. In May, Walmart upped its game, cutting the delivery period to two days and extending coverage to almost the entire continental United States.

However, Amazon Prime members have access to a host of additional services, including Prime Photo, Prime Music, Prime Video, Prime Pantry and Amazon Dash, and they can obtain free same-day delivery on hundreds of thousands of products in more than 35 cities globally.