As more baby boomers need hip replacements, health insurers like Humana and WellCare are turning into hot merger targets, according to Bloomberg. Both providers are generating record revenue as aging U.S. baby boomers drive an increase in enrollment in the government-sponsored program for the elderly. Insurers are also benefiting from expanded Medicaid coverage for the poor under Obamacare. Larger insurers such as Aetna and Anthem would like to continue expanding beyond coverage that's paid for by employers, and could be interested buyers. A deal for either Humana, valued at $27 billion, or Medicaid provider Centene, at $8.3 billion, would be the biggest acquisition of a U.S. managed-care provider in more than a decade. WellCare is smaller at $4.1 billion.