In its most recent set of results, France's BNP Paribas, the biggest owner of Greek debt outside Greece, said that it had written down the value of its Greek debt by 75% on its balance sheet.
And according to the Barclays report, Commerzbank is the biggest holder of Greek debt among Germany's banks. Its holdings of government debt have complicated its efforts to raise new finance to boost its balance sheet.
For the average investors, the effect of Tuesday's bailout is limited. Most insurance companies and investment firms have little or no exposure to Greece.
Some hedge funds have built up their holdings in Greek debt, but it is likely to be a relatively small amount, perhaps less than five billion euros.
It is thought some will refuse to sign up to the bailout deal and hope to be repaid in full.