Burford Capital (BUR) shares declined more than 2% Thursday after attorneys representing the US government asked a federal judge to block efforts to cash in on a share of the $16 billion court judgment awarded to investors after Argentina nationalized YPF (YPF) in 2012.

Burford has been seeking Argentina's 51% ownership stake in state-owned YPF as partial payment after US District Judge Loretta Preska last year said the Latin American country must compensate investor losses, ruling YPF's bylaws required it to make a tender offer to shareholders. She ruled in January the judgment was subject to immediate collection because Argentine officials failed to post a security deposit when it began its appeal.

The US Attorney's office in Manhattan late Wednesday urged Preska in a letter to reject Burford's bid to obtain the controlling stake in YPF, writing its "long-standing position that foreign sovereign property located abroad is not subject to execution in US courts."

But Burford said Thursday the US government does not oppose efforts to monetize the YPF judgment and instead was arguing "a narrow question of law" in Wednesday's letter to the judge.

"The (US Department of Justice) has previously taken the position that pursuing Argentina in the US courts for its breach of contract in this matter was appropriate," Burford said, further saying the government has not taken a formal position in the appeal.

Price: 14.27, Change: -0.34, Percent Change: -2.36