“Looking ahead, I believe the environment is going to remain challenging,” Corbat told his bank’s investors. “Europe’s issues, as the situation in Cyprus shows, still have the potential to rattle the markets and impact investor confidence.”

Hopefully, Citi’s clients weren’t on the line. Recently, the bank has made good money pushing a type of bond deal that packages together risky loans and sells them off to investors as highly rated investments. In the first quarter of the year, the bank was the biggest underwriter of collateralized loan obligations. Citi (C) is also back in subprime — earlier this month, it was one of the lead bankers on a $1.1 billion bond deal backed by auto loans to borrowers with low credit scores.

These are not the types of deals that investors buy when they are nervous, or should be, about the global economy. CLOs and subprime loan deals were popular before the financial crisis. They are hot again. Wall Street firms have sold nearly $30 billion in CLOs this year, more than triple what they sold in the same period a year ago, according to Thomson Reuters. Subprime auto loans deals hit $6.3 billion in the first quarter of this year, up nearly 30% from a year ago, according to trade publication Asset Backed Alert. Subprime home loan deals have been coming back as well, though they are still relatively rare. All the deals are part of Wall Street’s securitization machine, which packs up loans and then chops them up into bonds to be sold to investors — a good portion of which ground to a halt after the financial crisis.

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But the resurgence of Wall Street’s alphabet soup of investment products, which also includes asset-backed securities, or ABS, that are tied to credit cards and other consumer loans, is coming at a time when the banks’ top executives are still seemingly worried about the global economy. Caution was the general theme when banks reported their first quarter earnings in mid-April.

“We are very close still to the epicenter of the crisis,” Goldman Sachs CFO Harvey Schwartz told investors on his firm’s first-quarter conference call. “Macro uncertainty continues to be a meaningful consideration for the global marketplace.” And he’s not alone in waving the warning flag at Goldman (GS). Earlier this year, Gary Cohn, Goldman’s No. 2 executive, warned that investors in bonds should be worried about potential losses when interest rates rise. For its own trading book, Goldman has cut the amount of money it could lose if interest rates were to rise.

Yet, this isn’t holding back Goldman’s bankers. This year Goldman has sold more debt of companies rated CCC or worse than any other firm on Wall Street, according to research firm Dealogic. That’s two notches worse than what typically qualifies as junk. Goldman has sold $2.3 billion of the low-rated corporate debt, or nearly 20% of all similar deals this year. All told, Wall Street firms arranged $12.6 billion in sales of corporate debt rated CCC or lower in the first quarter, about $1.5 billion more than a year ago.

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But no corner of “high finance” is rebounding faster these days than the one for CLOs. The debt instruments act like mutual funds, buying up loans and selling off the portfolio to investors as bonds. Analysts say the deals are safer than they were before the financial crisis, because they are made up entirely of loans and not derivatives or other synthetic bets. What’s more, they are generally backed by more collateral than past deals.

But nearly all the CLOs being formed these days are invested in loans made to companies with lower credit ratings. What’s more, CLO managers have been putting more and more of their money into so-called covenant-lite loans, which have less protections for lenders. Morgan Stanley recently noted that more than half of the loans sold to non-bank lenders were covenant-lite.

In its recent quarterly earnings call with investors, Morgan Stanley CFO Ruth Porat said, “The periodic setbacks as evidenced in markets over the last several weeks is a reminder that the global economic recovery and market healing may not come in a straight line.” That, of course, has not kept Morgan Stanley (MS) out of the CLO market. Earlier this month, the bank was the lead underwriter of a $421 million CLO from New Jersey-based Seix Investment Advisors. It was the first CLO issued by Seix since 2007, and another sign that the market for these deals is back.

http://finance.fortune.cnn.com/2013/01/11/collateralized-loan-obligations/