FRANKFURT (Reuters) - Deutsche Bank shares were 4.9% lower in premarket trade on Monday after news that Germany's largest lender could be on the hook for up to 1.3 billion euros ($1.39 billion) in a yearslong lawsuit claiming it underpaid in its purchase of Postbank.

($1 = 0.9325 euros)

(Reporting by Tom Sims, Editing by Friederike Heine)