Greek bondholders are preparing to lose as much as 60 percent of their investments as European leaders try to impose a solution that reduces the nation's debt burden by enough to end the debt crisis.

“Everyone is coming to the conclusion that a much deeper restructuring is needed to make Greece in any way sustainable,” said Emiel van den Heiligenberg, chief investment officer of global balanced solutions at BNP Investment Partners in London, which oversees about $742 billion. “If the stock of debt doesn't diminish, then the problems are going to be bigger and bigger and Greece will require rescue package after rescue package.”

Greek 10-year bonds yielded 23.98 percent at 8:31 a.m. London time, with the price on the securities at 37.40 percent of face amount. The rate was 2,186 basis points, or 21.86 percentage points, more than benchmark German bunds and compares with a yield of 11.59 percent for similar-maturity Portuguese debt and 5.87 percent for Italian bonds.