Amazon.com Inc. said Wednesday that it is adding fresh groceries to its Same-Day Delivery service in more than 1,000 U.S. cities, allowing Prime subscribers to receive perishable items such as produce, dairy, meat and frozen foods within hours alongside everyday merchandise. The company aims to extend the program to more than 2,300 locations by the end of the year, calling the rollout one of the largest expansions of its grocery business to date. Prime members receive the service at no additional cost on orders above $25, or for a $2.99 fee when purchases fall below that threshold. Shoppers who are not Prime members can use the option for $12.99 per order. Amazon said its temperature-controlled fulfillment network and six-point quality check will keep perishable goods fresh during transit. The announcement rippled across the grocery sector: shares of Maplebear Inc., the parent of Instacart, fell about 11% in early trading, while Walmart Inc. slipped roughly 2% and Kroger Co. declined 3.5%. Amazon’s move intensifies competition with Walmart+, Instacart and traditional supermarket chains that already offer rapid grocery delivery. The e-commerce giant has been investing heavily in logistics, pledging $4 billion this year to expand same-day and next-day capabilities to thousands of additional U.S. communities. Integrating perishable goods into its broader delivery network underscores Amazon’s strategy of using speed and convenience to capture a larger share of the $1 trillion U.S. grocery market.