A lawyer in Bensalem, Pa., says he has begun an investigation into corporate actions involved the planned sale of New York-based NYMAGIC to ProSight Specialty Insurance Holdings announced last week.

The investigation involves possible breaches of fiduciary duty and other violations of the law by the NYMAGIC board of directors, according to lawyer Howard G. Smith.

Smith valued the deal at about $230 million, according to a statement.

The acquisition is expected to close in the fourth quarter.

ProSight Specialty Insurance was founded by CEO Joseph Beneducci and a group of senior executives from the property-casualty industry and is backed by affiliates of TPG Capital and GS Capital Partners.

The transaction will be 100% equity funded by ProSight. Completion of the transaction, which is expected to occur in the fourth quarter of 2010, is subject to the approval of NYMAGIC stockholders, customary closing conditions and regulatory approvals, officials said.

NYMAGIC specializes in underwriting ocean marine, inland marine and non-marine liability insurance, and whose agency subsidiaries specialize in establishing markets for such business. It owns and operates New York Marine And General Insurance Co., Southwest Marine And General Insurance Co. and Gotham Insurance Co.

Smith is seeking shareholders who might be interested in the investigation to contact him.