NEW YORK (The Deal) -- Health insurer Cigna  (CI) on Sunday rejected a $54 billion overture from fellow insurer Anthem (ANTM) made Saturday, noting the proposal minimizes shareholder value and comes with a laundry list of negatives for Cigna.

Bloomfield, Conn.-based Cigna released a letter saying it had been in good faith discussions with Anthem about a possible strategic combination for several months. However, Cigna complained that complications from Anthem's membership in Blue Cross Blue Shield programs, a massive data breach that exposed customer information in February and possible antitrust hurdles as some of the reasons a combination did not make sense.

Indianapolis-based Anthem outlined its non-binding proposal on Saturday, offering to purchase Cigna for $184 per share in cash and stock. That proposal valued the company at $53.8 billion, a 35.4% premium based on Cigna's closing price on May 28, Anthem said. The proposal consists of 31.4% Anthem shares and 68.6% cash. Anthem reiterated its commitment to the proposal on Monday, announcing no updates to the current plan.

"The proposal we submitted to Cigna presents significant and compelling value for shareholders in a transaction that would bring together two highly complementary platforms with a powerful growth potential," said Joseph Swedish, president and CEO of Anthem in a statement Monday. "Our management team has delivered consistently strong returns for shareholders and is absolutely confident in its ability to achieve the value inherent in this transaction. Grounded in this track record, we firmly believe that this combination will generate approaching $2 billion in synergies within two years post close and at least $17 adjusted earnings per share by 2018."

Another major point of contention for Cigna: Anthem wanted Swedish to assume four leadership roles including chairman of the board, CEO, president and head of integration. Cigna called the multi-appointments "disconcerting and risky" and called for a more balanced approach to governance.

The exchange between the two insurance providers is part of a highly anticipated wave of consolidation in the market. Late last month Humana (HUM) retained Goldman Sachs to assess offers for the company, which serves a large Medicare population. Aetna (AET) reportedly made an offer for Humana in the past week, according to the Wall Street Journal.

The Deal previously reported that the big five insurance providers -- Aetna, Cigna, Humana, United HealthGroup  (UNH) and Anthem, may start preying on each other. Insurers are not only reacting as though the Affordable Care Act is here to stay, but also on the belief that single-payer insurance could one day be a reality. The previous report noted that after Humana, Cigna was a likely next target.

Smaller insurers have also been targets. Last year, Anthem acquired Simply Healthcare Holdings for $800 million, a deal that helped Anthem bolster its presence and relationships inFloridain terms of its Medicaid and Medicare populations. At the time the acquisition was a part of Anthem's strategy for growth in its government business.

Anthem, which has a market capitalization of $43.6 billion was up over 4% at $172 on Monday. Cigna is up over 6% to $165.

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