Berkshire sold about 1.75 million shares this week at prices ranging from $59.93 to $60.94 apiece, according to a filing issued Wednesday. New York-based Moody’s has advanced 21 percent in 2013.

Moody’s plunged in February when its larger competitor, Standard & Poor’s, said it could face a U.S. lawsuit over inflated mortgage-bond ratings. Buffett, 82, has pared his stake from 48 million shares in 2009. Buffett has said Moody’s didn’t anticipate a slide in housing prices.

“What was once a bulletproof franchise may not be bulletproof,” the billionaire said in a 2010 Bloomberg Television interview. “It’s still quite a franchise.”

Buffett’s firm held 26.7 million Moody’s shares after this week’s transactions, the filing shows. Berkshire, based in Omaha, Nebraska, is still the largest shareholder in Moody’s, the second-biggest provider of credit ratings.

Moody’s declined 5 cents Wednesday in New York to $60.80. It advanced 14 percent in April and 11 percent in March after sliding 12 percent in February. Berkshire Class A shares gained 0.4 percent to $159,699.

Buffett didn’t immediately respond to an e-mailed request for comment sent to an assistant.