Sam's Club teams up with Instacart for same-day delivery

Walmart's Sam's Club is teaming up with delivery startup Instacart to offer same-day service in three U.S. markets.

The move is part of a strategy to better cater to shoppers who are shifting more of their purchases online.

The service will launch Tuesday in two Texas markets — Austin and Dallas-Fort Worth — and in St. Louis, Missouri. Sam's Club plans to expand it to other parts of the country. Instacart's other retail partners include CVS and Costco.

Sam's Club is seeking to make inroads on Amazon.com's Prime membership. It just added free shipping for its premium members on 95 percent of the items it sells online. Most shipping costs had been based on the item's size and weight, the shipping method and the delivery address.