1. Costco's Q1 earnings surpassed expectations at $4.50 per share. 2. E-commerce sales surged, and membership fees rose by 14%. 3. Despite strong results, Costco shares declined nearly 2% on Friday. 4. Year-to-date, Costco shares are down approximately 5%, underperforming rivals. 5. Rival Walmart shares gained nearly 30% this year, highlighting performance disparity.