Dec. 2 (Bloomberg) — U.S. corporate bond sales swelled to an annual record as a late-year rush by borrowers to lock in low interest rates pushed offerings for 2014 past $1.5 trillion.

Issuance was bolstered by heart-rhythm device maker Medtronic Inc.'s $17 billion bond sale yesterday, the largest dollar-denominated offering in more than a year, according to data compiled by Bloomberg. Internet commerce company Alibaba Group Holding Ltd. sold $8 billion last month, helping push this year's volume past the previous high of $1.494 trillion set last year.

Issuance is booming as companies have seized on record-low borrowing costs, boosted by the Federal Reserve maintaining its pledge this year to keep benchmark interest rates near zero for a "considerable time." After providing a 0.34 percent gain to investors last year, returns on the securities have grown to 6.9 percent, according to the Bank of America Merrill Lynch U.S. Corporate and High Yield Index.