ATHENS (Reuters) - Greece’s Alpha Bank said on Monday that it picked U.S. investment fund Davidson Kempner as its preferred bidder to buy a 10.8 billion euros ($12.81 billion) portfolio of non-performing loans in what will be Greece’s largest-ever sale of bad debt. Reuters had exclusively reported on Friday that Alpha Bank had selected Davison Kempner European Partners as the preferred bidder for the Galaxy transaction The sale also includes the disposal of Alpha’s bad loan servicing unit, Cepal. Davidson Kempner has valued the assets at about 290 million euros, a source told Reuters on Friday.