Bank of America (NYSE:BAC) wasn't the only one out shopping today. Health insurers UnitedHealth Group (NYSE:UNH) and Anthem (NYSE:ATH) also announced major acquisitions.

First, No. 1 health insurer UnitedHealth announced the acquisition of Mid Atlantic Medical Services (MAMSI) (NYSE:MME). At $18 a share in cash plus 0.82 UnitedHealth shares for each MAMSI share, the deal is valued at just under $3 billion.

For a reasonable 15 times earnings, UnitedHealth expands at a time when job cuts at employer-customers have eroded its potential customer base. Adding MAMSI's 2 million members, UnitedHealth will now cover 3.5 million members in the mid-Atlantic region and 20 million commercial and government members in all.

Yet, UnitedHealth will no longer be the largest U.S. health insurer.

Anthem also stepped up in a big way today, announcing the $16 billion acquisition of WellPointHealth Networks (NYSE:WLP). The combined entity will be industry's largest with 26 million members and $36 billion in revenues. The merger also creates a national provider of Blue Cross and Blue Cross Blue Shield plans with licenses in 13 states.

While Anthem is officially the buyer -- paying one share of stock and $23.80 in cash per WellPoint share -- WellPoint is actually the larger of the two, with 14 million members. Fittingly, the new company will be called WellPoint, Inc.

With UnitedHealth and Anthem both paying substantial premiums using their shares as currency, both stocks took hits today. Shares of UnitedHealth were down almost 5% to $51.74, while Anthem was down more than 9% to $70.13 in midday trading.

MAMSI, meanwhile, was up 10% to $59.19, and WellPoint gained almost 8% to $90.45.

Jeff Hwang can be reached at JHwang@fool.com.