NEW YORK—Arch Insurance Group, a division of Arch Capital Group Ltd., on Monday said it has formed two new principal underwriting groups—Arch Property & Casualty Group and the Arch Financial & Professional Liability Group—in its U.S.-based operations.

Michael Murphy was promoted to president of the property/casualty group in New York. Mr. Murphy most recently served as a senior executive vp of New York-based Arch Insurance Group.

David McElroy, who joined Arch Insurance Group from The Hartford Financial Services Group Inc. on June 8, will serve as president of the financial and professional liability group in New York. While at Hartford, Mr. McElroy served as president of the insurer’s specialty financial division.

Arch Insurance Group also announced that John Rafferty has joined the insurer as head of the executive assurance division of the financial and professional liability group, also in New York. Mr. Rafferty also formerly worked for Hartford in its financial products division.