The conceit that the five major commercial health insurers will consolidate to three seems to be dissolving, as four of those insurers called off a pair of mega-mergers on Tuesday. After 18 months of courtship among the Big Five starting in 2015, the outgoing Obama Justice Department’s antitrust division sued to block the $34 billion Aetna- Humana tie-up as well as Anthem’s $48 billion acquisition of Cigna. Federal judges blocked both transactions earlier this year. Anthem had planned to appeal but on Tuesday Cigna pulled the plug after Aetna and Humana did the same.

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