Concrete pouring during commercial concreting floors of building

Ambuja Cements—part of billionaire Gautam Adani’s ports-to-power business empire—agreed to buy a 47% stake in Orient Cement in a deal valued at 81 billion rupees ($963 million) as the Adani Group steps up acquisitions amid intensifying rivalry with tycoon Kumar Mangalam Birla.

After acquiring the stake from Orient Cement’s founders and other shareholders, Ambuja plans to buy another 26% stake at 395.40 rupees, Ambuja said in a statement late Tuesday. That’s a........

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