Piraeus Bank SA said it’s seeking to exchange almost 600 million euros ($686 million) of bonds to strengthen its capital base as the European Central Bank stress tests Greece’s biggest lenders and lawmakers prepare to recapitalize the banking system.

Piraeus asked holders of 365 million euros of senior unsecured notes due March 2017, 211 million euros of subordinated bonds maturing July 2016 and 19 million euros of perpetual junior subordinated securities to swap their debt for non-transferable receipts with the option to receive cash or shares, according to a regulatory filing on Thursday. The deadline for the exchange is Nov. 4.

The offers “reflect the fact that if state aid is required to meet any part of the additional capital requirements that may be imposed” as part of the assessment, “burden sharing will need to be achieved to the maximum extent possible through contributions by holders of equity, hybrid capital and subordinated debt,” Piraeus said in a regulatory filing on Thursday. The lender said it will also consider other means of burden sharing.

The ECB is reviewing the balance sheets of Greece’s four biggest banks -- Piraeus, National Bank of Greece SA, Eurobank Ergasias SA and Alpha Bank AE -- and will set the minimum regulatory capital they’re required to hold to pass the stress test. Greek lawmakers need to pass legislation this month to set the ground rules under which the banks will be recapitalized.

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