Warren Buffett's dealmaker closed the biggest 'blank-check' takeover ever this month. Here's why he may owe the Berkshire Hathaway chief for the deal.

• Warren Buffett's dealmaker struck an $11 billion deal to acquire MultiPlan this month, marking the biggest "blank-check" takeover to date.
• Former Citi banker Michael Klein got to know MultiPlan and its boss when he advised Buffett's Berkshire Hathaway on a potential purchase of the healthcare group in 2013, the Financial Times reported on Tuesday.
• Klein's history with Buffett includes persuading him to invest in Dow Chemical in 2009, and helping to convince him not to pursue a takeover of Unilever by Kraft Heinz in 2017.
• The Wall Street rainmaker's advisory team includes ex-Apple design chief Jony Ive, and Berkshire holds a $96 billion stake in Apple.
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Warren Buffett's dealmaker recently struck the biggest "blank-check" takeover in history. He reportedly owes the Berkshire Hathaway chief for putting the target on his radar.

Michael Klein, a former Citi banker, closed the $11 billion acquisition of US healthcare group MultiPlan by his Churchill Capital III investment vehicle earlier this month.

Churchill Capital III is one of Klein's four SPACs, or special-purpose acquisition vehicles, which are designed to take companies public by acquiring or merging with them.

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Klein advised Berkshire when it looked at acquiring MultiPlan in 2013, the Financial Times reported on Tuesday. The deal didn't happen, but Klein became familiar with both the company and CEO Matt Tabak during that period, the newspaper said.

Klein has worked with Buffett on several deals over the years. He persuaded the famed investor to buy $3 billion worth of Dow Chemical's preferred stock as part of the chemicals giant's $15 billion takeover of rival Rohm & Haas in 2009, according to Institutional Investor.

He also helped to convince Buffett to scrap Kraft Heinz's proposed $143 billion takeover of Unilever in 2017. The banker called the Berkshire chief to highlight political concerns around the deal and connect him with Unilever's boss, then Kraft Heinz pulled its offer hours later, CNBC reported.

Other connections to Buffett

Churchill Capital III is buying MultiPlan from Hellman & Friedman, which itself acquired the healthcare group from a division of CV Starr & Co, an insurance-and-investing conglomerate run by former AIG CEO Hank Greenberg that people have compared to Berkshire.

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Klein's firm, Klein & Co, houses a group of experts called Archimedes Advisors. They include former Ford CEO Alan Mulally, ex-CBS chairman Joe Ianniello, and former Apple design chief Jony Ive, the Financial Times said.

Berkshire is one of Apple's biggest investors with a $96 billion stake. Buffett has described the tech giant as Berkshire's "third business" after insurance and railroads.

Klein's record for the largest US-based SPAC IPO is under threat from billionaire Bill Ackman, who hopes to raise $4 billion for his SPAC, Pershing Square Tontine Holdings, when it goes public this week.

Ackman is a longtime admirer of Buffett and counted Berkshire as one of his biggest holdings until recently.