Unless you are participating in a limited-time promotional offer, you will earn one ThankYou Points for every dollar you spend on purchases (no other transactions qualify to earn ThankYou Points). However, for the first twelve months that you are a cardmember, you will earn five ThankYou Points at supermarkets, drugstores and gas stations which are defined as follows. Supermarkets are stand-alone merchants that primarily sell a complete line of food merchandise for home consumption. Drugstores are stand-alone merchants that primarily sell prescription and proprietary drugs and nonprescription (over-the-counter) medicines. Gas stations are stand-alone merchants that primarily sell vehicle fuel for consumer use.

Purchases not eligible to receive the five points include, but are not limited to, purchases made at warehouse clubs, discount stores and convenience stores. Online and catalog purchases are not eligible to receive five ThankYou Points unless the merchants appropriately identify the transactions.

https://www.accountonline.com/ACQ/DisplayPage?docId=CompleteDetailsPop&app=UNSOL&sc=4D3Z58K6&siteId=CB&langId=EN&BUS_TYP_CD=CONSUMER&B=M&DOWNSELL_LEVEL=0

Thats the terms and conditions from citi's website.  According to their definition of Supermarkets, I dont think Walmart counts towards the earning points.  Just call citi to make sure.  And, please share that info with us what you found out.  Thx.