Jim Walton, 76, saw his net worth reaching $102.6 billion Monday while his brother Rob, 79, posted $100.4 billion, according to the Bloomberg Billionaires Index.
Their sister Alice, 74, stood at $99.7 billion.
As of Wednesday their net worths have dropped by around 1.6-1.8% each.
Walmart shares have been rising steadily in recent weeks and reached an all-time high of over $80 Monday.
They have surged 53% this year as its e-commerce business has drawn in more middle-class customers looking to tighten their budgets, Bloomberg reported.
The Waltons have consistently held a position among the world's wealthiest families, with a combined net worth now exceeding $350 billion.