Activist investor Carl Icahn, mulling a potential board fight, on Thursday sued Occidental Petroleum Corp. for records related to the oil-and-gas firm’s “bet-the-company” deal earlier this month to acquire Anadarko Petroleum Corp. in what he said was a “fundamentally misguided and hugely overpriced” transaction.

The lawsuit, filed in Delaware Chancery Court, came just weeks after Houston-based Occidental outbid Chevron Corp. for the right to buy Anadarko—based in The Woodlands, Texas—for $57 billion in a merger of two Texas oil-and-gas exploration giants.