(Bloomberg) — Cigna Corp. rejected Anthem Inc.'s $47 billion takeover bid, saying it was inadequate, not in the best interests of shareholders and that Anthem's management wasn't fit to lead a merged insurance giant.

Anthem on Saturday offered to buy the smaller health insurer in what would be the biggest takeover ever in a U.S. industry on the verge of major consolidation. Insurers such as Anthem are searching for ways to cut costs and keep expanding profits amid a surge in enrollment from Obamacare and new rules from the law.

Unlike the drug industry, where big pharmaceutical manufacturers have gobbled up smaller biotechnology companies, Anthem and Cigna are well-established companies with their own strategies. That means that while there will be takeovers, they won't happen without a struggle.