Furthermore, regarding increased risks, the presentation says catastrophe exposures from the combined company would be “well beyond our current thresholds,” and a higher level of financial leverage “reduces flexibility after major industry events.”

The presentation says Transatlantic has outperformed Validus in its core line of property business, claims Validus' commitment to casualty business is uncertain, and says the deal may lead to downgrades by Standard & Poor's and A.M. Best.

Transatlantic's board says it has reached out to a number of parties and “conducted due diligence with three parties in October 2011, including Validus.”

The presentation adds, “The Transatlantic board continues to be open to a transaction that would maximize our stockholders' value. If no transaction takes place, we are confident we will be able to achieve our goals and increase stockholders' value with our current path.”

For Validus' part, Chairman and Chief Executive Officer Edward J. Noonan says in a statement, “Despite months of deliberation, the Transatlantic board still fails to act to maximize value for Transatlantic stockholders by entering into a premium transaction with Validus. As we have said since the beginning of this process, we believe that the Transatlantic board should act in the best interests of its stockholders and we are fully committed to making our increased offer directly available to Transatlantic stockholders.”

Validus says the Transatlantic board makes has “a number of inaccurate statements regarding Validus' increased offer” in its presentation.

“Validus believes that Transatlantic's track record of statements on ratings, capital structure, reserve development, measure of 'risk-adjusted' returns and integration risk call into question the credibility of the Transatlantic board,” the company says.

Validus says in its deal, investors get a combined company “led by a board and management team with deep industry knowledge and hundreds of millions invested who are committed to maximizing shareholder value.”

The Bermuda-based company says it will soon mail to Transatlantic stockholders consent solicitation materials, “including a BLUE consent card, which will contain important information as to why Validus believes Transatlantic stockholders need to replace the Transatlantic board with Validus' highly qualified and independent nominees.”