If yield is a drug, Wall Street's working overtime to supply it.

Investors' global reach for income is giving America's largest banks their biggest surge in risky loan sales on record. Goldman Sachs Group Inc. and Bank of America Corp. on Tuesday joined JPMorgan Chase & Co. and Citigroup Inc. in reporting first-quarter gains of almost 40% in underwriting revenues.

"There's a narcotic need for higher yield by debt investors, and the Street is going to create the deals to satisfy that," said David Hendler, founder of Viola Risk Advisors. "Those with the better corporate-finance Rolodexes — Goldman Sachs, Bank of America, JPMorgan and Citigroup — are going to see the best deal flow because they're connected to the mid-level companies that seek leveraged lending. It's giving their earnings a boost."