The market for corporate borrowing through commercial paper contracted for an eighth week, reaching the lowest level in 21 months, as issuers reduced the amount of short-term IOUs and sold longer-dated corporate bonds, with yields at about record lows.

The seasonally adjusted amount of U.S. commercial paper dropped $19.2 billion to $924.4 billion outstanding in the week ended yesterday, the Federal Reserve said today on its website. That's the longest stretch of declines in a year and the lowest level since the market touched $916.8 billion in the period ended Jan. 19, 2011, according to Fed data compiled by Bloomberg.

Borrowers are taking advantage of unprecedented low interest rates to sell longer-term company bonds and to reduce the risk of a squeeze in short-term lending amid Europe's persistent debt crisis.