Eurobank, Greece's fourth-largest lender, has completed the acquisitions of New Hellenic Postbank and Proton Bank.
The institution took on the other firms from the country's bank rescue fund as Greece continues to consolidate its struggling financial sector.
Last year, banking regulators determined that the state-owned Hellenic Postbank was no longer a viable company after it sustained heavy losses. As a result it was split into "good" and "bad" segments.
Greece's Financial Stability Fund (HFSF) gave Eurobank the green light to buy the two small lenders last week.
The sale of New Hellenic Postbank and Proton Bank had to be completed by 15 July as a condition made by the country's international lenders for the release of more funds from the rescue package keeping it going.
HFSF owns all of New Hellenic Postbank and also has a 93.6 per cent stake in Eurobank after recapitalising it last month.
By Asim Shah