The U.S. government may lose its AAA credit rating even if lawmakers reach a plan to avoid a default, said Mohamed A. El-Erian, whose Pacific Investment Management Co. is the world's largest manager of bond funds.

"In most likelihood, a last-minute political compromise will avoid a default but will leave the AAA rating extremely vulnerable," El-Erian, the Newport Beach, California-based chief executive officer and co-chief investment officer at Pimco, wrote in an e-mail. "Stock markets around the globe will look to price in a greater uncertainty premium on account of political squabbles in the world's largest economy and the increasing risk that it may lose its sacred AAA rating."

House Speaker John Boehner plans to press ahead with a shorter-term increase in the U.S. debt limit than President Barack Obama has requested, he told lawmakers yesterday, defying a veto threat and signaling continued stalemate in the U.S. Congress as time runs short for a deal. The impasse has boosted the chance S&P will cut the U.S. credit rating from AAA within three months to 50 percent, the company said July 21.