European bank debt, once an investment pariah, is suddenly popular.
In recent weeks, money managers have been readily buying the new bonds of the region's financial institutions, deals that just months ago would have seemed unpalatable. Bank of Ireland, which received a bailout in 2010, sold $1.3 billion of bonds on Tuesday and found strong demand. It was the largest offering by an Irish bank without a government guarantee in almost three years.
The gradual thawing of the capital markets is a good sign for the region's banks. In the midst of the crisis, institutions, especially in troubled economies like Ireland and Portugal, have been struggling to raise money from private investors. The latest deals will help bolster banks' capital levels and strengthen their balance sheets.
But the bonds could leave investors exposed, especially given the precarious situation in Europe. The sovereign debt crisis continues to weigh on the economy. The financial markets remain volatile. And profit at the region's banks is flagging.
(Read More: Euro Zone Slips Into Second Recession Since 2009)
"It's a great time to be issuing high-yield debt but not to be investing in it," said Robin Doumar, managing partner at the private equity firm Park Square Capital.
For now, bondholders are taking comfort in the policy makers' response to the sovereign debt crisis.
In late August, the European Central Bank began an unlimited bond-buying program aimed at lowering countries' borrowing costs and breathing life into local economies. By essentially offering a blank check to help Europe's troubled governments, policy makers calmed short-term fears that some of the region's banks might need to be bailed out, reviving interest in the companies' bonds.
"The biggest driver of demand has been the policy responses from the European Central Bank," said Melissa Smith, head of European high-grade debt capital markets at JPMorgan Chase in London. "It's provided stability as policy makers have stated their commitment to preserving the euro zone."
With interest rates at record lows, European bank debt looks especially appealing to investors.
On Thursday, the British bank Barclays sold $3 billion of 10-year bonds at 7.6 percent. The Portuguese lender Banco Espírito Santo recently issued $958 million worth of debt at 5.9 percent.
By comparison, a 10-year Treasury is paying 1.8 percent. Germany has offered a negative yield on some of its sovereign debt maturities this year.
Even the yields on junk bonds, the risky corporate debt that pays high interest rates, are coming down as investors pile into such securities. The average yield is now just 5.8 percent, according to a Bank of America Merrill Lynch index. Historically, they have paid 10 percent or even more.
(Read More: Junk Bonds Grow More Popular and Turn Even Riskier)
"There's been a huge contraction," said Robert Ellison, head of European debt capital markets for financial institutions at UBS in London.
The industry has been quick to capitalize on investors' desperate hunt for returns. Banks in Europe have issued a combined $318 billion of unsecured debt so far this year, almost triple the amount raised by their American counterparts, according to the data provider Dealogic.
The capital markets are being discerning. This year, well-financed companies in Northern Europe, like Nordea Bank of Sweden, have been able to sell the largest lots of bonds at relatively reasonable rates. Smaller banks, particularly in Southern Europe, have had to offer investors better rates to win support for their bond deals.
Even so, it is a stark contrast from almost a year ago. With the capital markets paralyzed, the European Central Bank then had to step in to stabilize the banks, offering $1.3 trillion in short-term, low-cost loans to financial companies.
As they find renewed interest from private investors, European banks can more easily raise money, fortifying their balance sheets in case of unexpected losses. At regulators' behest, financial institutions in the region have been increasing their capital levels.
(Read More: Growing Signs of Europe Banking Turnaround)
But bond investors, in their thirst for yield, may be overlooking signs of potential trouble.
Barclays, for instance, sold a controversial type of debt, known as contingent convertible bonds. With these so-called CoCo bonds, investors can be wiped out if the bank's capital falls below a certain threshold. While Barclays' balance sheet is in good shape, bondholders' willingness to accept such conditions highlights the risks in the market. Traditional bondholders can usually recoup at least some of their principal even if a company goes bankrupt.
At the same time, many European financial institutions are still in fragile shape. The Bank of Ireland, in which the Irish government still has a small stake, is struggling to divest itself of many risky loans that it made before the financial crisis. Portugal's economy is also expected to contract 3 percent this year, which will probably depress the earnings of Banco Espírito Santo.
The question for investors is whether the reward is worth the risk.