February already ranks as the ninth-largest month on record in issuance of U.S. dollar-denominated high-grade debt, according to Dealogic. The month's tally stands at $67 billion, and $9 billion for this week alone, in bonds not backed by the Federal Deposit Insurance Corp.

"The companies that have accessed the market have been predominately stronger, better-capitalized businesses, with the wherewithal to handle an economic downturn," said Tim Compan, corporate-bond portfolio manager at Cleveland-based Allegiant Asset Management. "There has, and will be, indigestion as spreads tighten, but for the most part, new issues have been well-received."