Capital markets lawyers expected a modest surge in high-yield debt last year, but what they got was an absolute bonanza. Record-low interest rates and an onslaught of debt maturities in a market that had been somewhat inaccessible in recent years triggered a borrowing blitz in 2010. Offerings soared 80 percent, to 686 last year, as the total value of these issuances rose 85 percent, to $335.3 billion, according to Thomson Reuters. “We thought there would be an increase in high-yield offerings, but no one had the crystal ball to predict that 2010 would blow the doors off 2009,” says Arthur Robinson, a partner in Simpson Thacher & Bartlett’s capital markets group.

Simpson Thacher maintained its position as top issuer’s counsel for high-yield debt, with 45 issues totaling $23.3 billion. The firm narrowly beat out runner-up Skadden, Arps, Slate, Meagher & Flom’s 36 offerings worth $23.1 billion.

Cahill Gordon & Reindel led the roster of high-yield underwriter’s counsel , advising on 190 offerings worth $100.4 billion–more than double its offerings’ proceeds for 2009. Davis Polk & Wardwell, which continued to do work for longtime client Credit Suisse Group AG, moved up two spots to fourth place (by volume), with 46 offerings valued at $21.4 billion–nearly tripling its 2009 proceeds. One notable jump came from Dewey & LeBoeuf, which advised zero underwriters on high-yield offerings in 2009, but handled seven last year. Frank Adams, global cochair of Dewey’s corporate finance practice, attributes the increase to the addition of corporate finance partner John Cobb in late 2009, who “helped extend the firm’s relationship with investment banks,” says Adams.

Last year “was the perfect confluence of events for a vibrant high-yield market,” says Robinson, who represented JP Morgan Securities LLC and Barclays Capital Inc. in the financing of 3G Capital’s acquisition of Burger King Holdings, Inc. Kirk Davenport II, Latham & Watkins’s capital markets cochair, also noted 2010′s ideal conditions: “Interest rates were so low in 2010, it was basically free money.” Plus, he says, “a whole boatload of high-yield debt is maturing in 2013, and companies chose to refinance that debt last year.”

And investors were biting. They saw corporate debt as a better source of yield than Treasury bonds or the stock market, says Michael Kaplan, a partner in Davis Polk’s corporate department.

Investment-grade debt experienced a milder uptick than high-yield for the second year in a row but still saw industrywide proceeds increase 11 percent. On the issuer’s counsel side, Davis Polk beat out Sullivan & Cromwell, 2009′s number one, to clinch the top spot with 84 offerings that raked in $72.3 billion. In 2009 Davis Polk handled 34 offerings. For underwriters, Sidley Austin led the way (by number of issues) with 115 offerings and proceeds of $68.2 billion. That boosts it one spot from 2009, when it worked on 78 offerings.

What’s on tap for 2011? More of the same, says Adams. “Term debt will continue to be refinanced in the high-yield market, and we expect more leveraged finance transactions,” he says. Let the good times roll.