Grocery Delivery Service Instacart Raises $44 Million By William Alden Companies like Uber and Airbnb have prospered by allowing people to sell their services to strangers on a smartphone-powered network. Now venture capitalists are betting that a young start-up can use that principle to achieve success in the grocery business. Instacart, a two-year-old grocery delivery company, announced a $44 million round of financing on Monday led by Andreessen Horowitz. Three venture capital firms that previously invested in the company, Sequoia Capital, Khosla Ventures and Canaan Partners, participated in the latest round. The company, which is based in San Francisco, lets customers shop online from grocery stores in their area. The orders are filled by other people who have signed up to be shoppers and who…