More than five months ago, the Federal Reserve and Office of the Comptroller of the Currency (OCC) told some of the biggest banks to improve underwriting standards for non-investment-grade loans. The market is showing few signs of tightening as lenders chase lucrative fees.

Banks are arranging junk-rated deals that leave companies with debt levels exceeding guidelines set by regulators. Among them: the $1.7 billion of loans led by UBS AG and Deutsche Bank AG last month to finance KKR & Co.'s purchase of a majority stake in Sedgwick Claims Management Services Inc., and the $700 million loan Credit Suisse Group AG arranged in January for Applied Systems Inc., a maker of software for insurance companies.

Bank supervisors are insisting on minimum standards as they seek to avoid a repeat of the losses that occurred during the credit crisis, which sent the global speculative-grade default rate to more than 13 percent in 2009, the highest since the Great Depression. The persistence of deals with questionable terms shows that, so far, regulators are having trouble deterring excessive risk-taking simply by asking.