Allen & Overy has suffered a blow to its New York operations, with two heavyweight partners quitting to join Shearman & Sterling.

The Magic Circle firm's U.S. leveraged finance group co-heads – partners Alan Rockwell and Michael Chernick – have left to join the U.S. firm.

Rockwell was part of a trophy finance team hire made by A&O three years ago in New York, described as a "game-changer" by the firm. He joined from White & Case, where he had been a partner for nine years.

The following year, A&O hired Chernick as part of another star team hire in New York, this time from Paul Hastings, where Chernick had spent 20 years.

Shearman senior partner David Beveridge said in a statement: "We are committed to serving the needs of our clients including providing them with outstanding talent across our platform. The opportunity to add Alan and Michael to our team is significant for the firm as we look to further cement our position as one of the leading transatlantic leveraged finance firms."

Both partners specialise in high yield finance matters and follow the addition of star London high yield partner Ward McKimm from Magic Circle firm Freshfields Bruckhaus Deringer last year.

Last month, A&O was hit by the departure of a corporate heavyweight partner duo to another U.S. firm, when Skadden Arps Slate Meagher & Flom hired George Knighton and Simon Toms in London.

A&O recently affirmed its commitment to its U.S. ambitions, following the breakdown of its merger talks with U.S. firm O'Melveny & Myers.

It hired senior managing director Julian Moore from investigative and advisory service firm K2 Intelligence as a partner last month.

Earlier in the summer, it also expanded with the addition of a counsel from U.S. firm Cahill Gordon & Reindel. Jin Hee Kim joined the Magic Circle firm's New York office leveraged finance practice as a partner.

An A&O spokesperson said in a statement: "We thank Alan Rockwell and Michael Chernick for their contributions during their time at A&O and wish them all the best for the future. Our New York leveraged finance practice continues to be a robust and integral part of A&O's global offering.

"We are one of a very limited number of firms that can field a global leveraged finance practice, combining U.S.- and English-law leveraged finance capability, both loans and high yield."