Warren Buffett has been a fixture on rich lists for decades, while Charlie Munger rarely gets a look in. The famed investor's right-hand man would be worth over $10 billion today if he kept all of his Berkshire Hathaway stock.

Munger, Berkshire's vice-chairman since 1978, owned 4,033 Class A shares of the company as of October 5, regulatory filings show. That stake is worth $2.1 billion today, based on the $522,700 closing price of the A shares on Friday. The 99-year-old has other notable assets, including over $100 million worth of shares in his beloved Costco.

Forbes pegs Munger's net worth at $2.5 billion, and places him around 1,200th in its real-time wealth rankings. He doesn't even make the cut for the Bloomberg Billionaires Index, which only extends to the world's 500 wealthiest people. In contrast, Buffett holds top-10 spots on both lists with an estimated $116 billion fortune.

Why is Munger's net worth so much smaller? Mostly because Buffett has always owned a much larger Berkshire stake, but also because Munger has sold or donated more than 75% of his Berkshire stock over the years.

Buffett's business partner owned 18,829 A shares — 1.6% of the outstanding stock — in 1996, the earliest year for which disclosures are available. That stake would be worth about $10 billion at Berkshire's current stock price, and would have been valued close to $11 billion when the stock hit a record high of over $566,000 in September.

A $10 billion net worth would rank Munger in the top 200 spots on both Forbes and Bloomberg's lists, ahead of Salesforce CEO Marc Benioff, fashion icon Ralph Lauren, and PayPal and Palantir cofounder Peter Thiel.

Munger could have been even richer, as he likely owned more Berkshire shares prior to 1996. His stake primarily stemmed from Berkshire's takeover of two businesses that he partly owned, Blue Chip Stamps and Diversified Retailing, in the late 1970s and early 1980s.

"It would be fair to say that at his peak ownership of Berkshire, he'd own about five times the number of shares that he owns today, making his position north of $10 billion," Chris Bloomstran, the president of Semper Augustus Investments and a longtime Berkshire shareholder, told Insider.

It's worth underscoring that Munger has intentionally pared his Berkshire stake to fund his charitable giving. For example, he donated 77 A shares worth about $40 million to a library and art gallery just this month.

"I'm deliberately taking my net worth down," he told The Omaha World-Herald in 2013. "My thinking is, I'm not immortal," he continued, "and I won't need it where I'm going."