A five-way takeover frenzy broke out into the open over the weekend, with Anthem Inc. taking its $47.5 billion bid to buy Cigna Corp. public in a contentious move that shows the pressure the big health insurers are under to quickly find merger partners.

Anthem said Saturday it has offered $184 a share in cash and stock for Cigna. It made the bid public to appeal to Cigna shareholders in the hopes they will force the company to do a deal, according to a person familiar with the matter.

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