Thomas Leonardi, the Connecticut insurance commissioner, plans to leave the Connecticut Insurance Department Dec. 11.

Leonardi will become a senior advisor for insurance at Evercore, an investment bank that manages assets for many insurers, according to Connecticut Gov. Dannel Malloy, D.

Malloy, who won re-election Nov. 4, named Leonardi to lead the Connecticut department in February 2011. Leonardi succeeded Thomas Sullivan. Sullivan left to take a job in the Hartford office of PricewaterhouseCoopers L.L.P.

Before Leonardi took over as the Connecticut commissioner, he was chairman of Northington Partners Inc., an insurance investment firm. Earlier, he worked on insurance company mergers, acquisitions and venture capital deals at Conning.

While at the Connecticut department, Leonardi has been active at the National Association of Insurance Commissioners (NAIC), in the new U.S. federal financial services agencies created by the Dodd-Frank Act, and at the International Association of Insurance Supervisors (IAIS). He has been active in slowing efforts to have the United States make its own financial services regulatory system equivalent to Europe’s new Solvency 2 system.

In Connecticut, actuaries under Leonardi have frequently required health insurers to reduce proposed individual policy rate increases, and they have blocked many proposed long-term care insurance (LTCI) rate increases.