Sales of corporate bonds from the U.S. to Europe and Asia are accelerating, marking their busiest January ever following unprecedented issuance in 2012, as borrowers seek to lock in yields at about record lows.

Berkshire Hathaway Inc., the investment firm run by Warren Buffett, and Fairfield, Connecticut-based General Electric Co. led issuers selling $409.5 billion of bonds this month, up from $226 billion in December and surpassing the $407.2 billion sold in January 2009, according to data compiled by Bloomberg. Sales last year soared 20.5 percent to $3.96 trillion.

Treasurers are tapping the company bond market as Bank of America Corp. says a “disorderly rotation” from debt into equities may cause borrowing costs to rise. Yields for the most creditworthy to the riskiest borrowers are climbing this month for the first time since May.

“The market has been obviously red hot, so that brings every issuer out of the woodwork,” Marc Gross, a money manager at RS Investments in New York who oversees $3 billion in fixed- income funds, said in a telephone interview. “The market is receptive to issuers so they’ll keep coming until the market gets fatigued.”

Yields increased to 3.36 percent yesterday from 3.28 percent on Dec. 31, the first monthly increase since a 9 basis- point rise to 4.23 percent in May, according to the Bank of America Merrill Lynch Global Corporate & High Yield index. The extra yield investors demand to own company debentures rather than government debt has fallen to 209 basis points, or 2.09 percentage points, from 221 at year-end.

Berkshire, GE

Berkshire, which its 82-year-old chairman built into a $241 billion company in market value with takeovers and stock picks, raised $2.6 billion in a four-part offering, Bloomberg data show. The sale from the Omaha, Nebraska-based company included $1 billion of 4.5 percent, 30-year debt that yields 140 basis points more than similar-maturity Treasuries.

GE, the largest maker of engines for jet planes, raised $4 billion in a three-part sale, Bloomberg data show. The offering included $2 billion of 3.1 percent, 10-year notes at a spread of 122 basis points. Those bonds have fallen 0.8 cent from the issue price on Jan. 3 to 98.99 cents on the dollar to yield 3.22 percent as of 8:53 a.m. in New York, according to Trace, the bond-price reporting system of the Financial Industry Regulatory Authority.

Investment-grade bondholders may see “massive outflows” this year as investors shift their allocations toward stocks as the risk of higher interest rates rises, analysts led by Hans Mikkelsen wrote in a Jan. 28 report.

The potential rotation is “the biggest risk to investment grade this year and the one we are getting increasingly concerned about,” they wrote.