In emerging markets, relative yields widened 1.4 basis points to 276.6 basis points, according to JPMorgan Chase & Co.’s EMBI Global index. The measure ended last year at 265.8.

Bonds of Rio de Janeiro-based Petrobras were the most actively traded dollar-denominated corporate securities by dealers last week, accounting for 5.2 percent of the volume of trades of $1 million or more, according to Trace, the bond-price reporting system of the Financial Industry Regulatory Authority.

The company’s $3.5 billion of 4.375 percent, 10-year notes rose 1.6 cents from their issue price on May 13 to 100.42 cents on the dollar to yield 4.32 percent.

Corporate bond offerings in the U.S. have exceeded the $29.5 billion weekly average for the past 12 months in each of the past five weeks, propelling sales to the busiest pace ever.

Issuance has reached $689.6 billion this year, exceeding the $593.2 billion in the corresponding period of 2012. Globally, offerings total $1.66 trillion, the fastest pace behind $1.8 trillion in the similar timeframe in 2009.

‘Substantial Appetite’

“Investors worldwide still have a substantial appetite to own high-quality, fixed-income assets,” RBS’s Marrinan said. “The crowding-out effect of central bank purchases of government securities is forcing the investors into a diminishing pool of buyable high-quality corporate exposure.”

Petrobras split its offering in six parts, including fixed- rate bonds due in three, five, 10 and 30 years as well as three- and five-year floating-rate bonds, Bloomberg data show.

Apple Inc. sold $17 billion of bonds in the biggest corporate offering on record on April 30 as the iPhone maker issued its first debentures since 1996, Bloomberg data show. The sale included $4 billion of 1 percent, five-year notes paying a relative yield of 40 basis points and $5.5 billion of 2.4 percent, 10-year securities with a 75 basis-point spread.

Proceeds from the Apple offering will help finance a $100 billion capital reward for shareholders. The sale was a “great example of companies using funds for equity-friendly behavior,” John Lonski, chief economist for Moody’s Capital Markets Research Group in New York, said in a telephone interview.