Eternal Ltd. and Swiggy Ltd. got the 10-minute delivery party going in India. Now, e-commerce titans Amazon.com Inc. and Walmart Inc.'s Flipkart are looking to crash it. Eternal, whose Blinkit does doorstep delivery of everything from eggs to electronics within minutes, has slipped 28% from its October all-time high as of Thursday's close, while rival Instamart's owner Swiggy has plunged about 47% from its recent peak in September. That adds up to a selloff of more than $15 billion for the duo as investors get spooked by the onslaught of competition.