In October, weeks before anyone had heard of what’s now known as the novel coronavirus, Alice Walton of Fort Worth led Texas’ billionaires club. And she still does, although her net worth has plunged by $1.8 billion since then.

But among the 20 Texans who ranked highest on October’s Forbes 400 list of the richest people in the U.S., no one has seen their fortunes fall more — due to coronavirus-inflicted economic damage and a simultaneous drop-off in the oil and gas market — than Dallas pipeline executive Kelcy Warren.

A CultureMap review of Forbes’ daily real-time data shows Warren’s estimated net worth plummeted from $4.3 billion in October to $2.3 billion as of March 26. That’s a decline of $2 billion, or 46.5 percent — the biggest percentage crash among the 20 billionaires.

By comparison, Walton’s net worth went from $51.4 billion in October to $49.6 billion as of March 26. That’s a difference of $1.8 billion, or a relatively meager 3.5 percent.

Somewhat surprisingly, three of the 20 billionaires watched their fortunes rise or stay flat during the October-March period.

The net worth of Dallas Mavericks owner Mark Cuban jumped 4.9 percent, from $4.1 billion to $4.3 billion, according to Forbes. Pro sports mogul Stan Kroenke, who owns a 520,000-acre ranch west of Wichita Falls, witnessed a 3.1 percent spike in his net worth, which shot up from $9.6 billion to $10 billion. The net worth of Austin venture capital entrepreneur Robert Smith remained steady at $5 billion.

Right behind Warren for the most severe decrease in net worth among the 20 Texas billionaires is Robert Rowling of Dallas, owner of the Omni Hotels and Gold’s Gym chains. Both Omni and Gold’s are in two business sectors that have been slammed hardest by the coronavirus-fueled economic downturn.

According to Forbes, Rowling’s fortune sank from $5.5 billion in October to $3.3 billion as of March 26, down 40 percent.

Next in line to see their net worth fade were four Houston siblings and pipeline heirs: Randa Duncan Williams, Dannine Avara, Scott Duncan, and Milane Frantz. From October to March, each lost 38.1 percent of their net worth, which tumbled from $6.3 billion to $3.9 billion.

Here’s how the rest of the 20 billionaires have fared between October and March, in descending order of their percentage losses.

• Austin vodka kingpin Bert “Tito” Beveridge — $4.2 billion to $3.2 billion, 23.8 percent.
• Houston energy executive Richard Kinder — $7.5 billion to $6.1 billion, 18.7 percent
• Dallas banker and real estate investor Andy Beal — $9.8 billion to $8 billion, 18.4 percent.
• Austin tech titan Michael Dell — $32.3 billion to $26.9 billion, 16.7 percent.
• Dallas oil and gas heir Ray Lee Hunt — $5.2 billion to $4.5 billion, 13.5 percent.
• Fort Worth oil heir Robert Bass — $4.9 billion to $4.5 billion, 8.2 percent.
• Dallas Cowboys owner Jerry Jones — $8.6 billion to $8 billion, 7 percent.
• Houston restaurant honcho and Houston Rockets owner Tilman Fertitta — $4.9 billion to $4.6 billion, 6.1 percent. (According to the Bloomberg Billionaires Index, his fortune has slipped to $3.2 billion.)
• Margot Birmingham Perot of Dallas, widow of tech entrepreneur H. Ross Perot — $4.2 billion to $4 billion, 4.8 percent.
• Walmart heiress Ann Walton Kroenke, who lives with husband Stan near Wichita Falls — $7.5 billion to $7.3 billion, 2.7 percent.