The myriad companies of Warren Buffett’s Berkshire Hathaway Inc. have run completely independently of each other for decades. That isn’t always the case any longer.

Top executives from Berkshire units now gather regularly to share strategies and best practices. Some of these companies participate in purchasing cohorts to take advantage of group rates for items like travel and raw materials. Last year, employees from more than 40 Berkshire businesses met in the firm’s headquarters city of Omaha, Neb., to discuss sustainability.

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