Logo of Warren Buffett’s Berkshire Hathaway Inc. Warren Buffett’s Berkshire Hathaway Inc. reached a deal to buy Occidental Petroleum Corp.’s petrochemical business for about $9.7 billion in cash.   If the deal closes, it would be the biggest purchase for Berkshire since its$11.6 billion buyout of insurance firm Alleghany Corporation in 2022 and expand its chemical portfolio beyond Lubrizol.   The latest move marks billionaire Buffett's return to the search for good deals after years of abstaining from maj ...