The Frankfurt-listed company, also called O2, is expected to begin trading today at €5.60 per share.
The IPO is Germany’s biggest since 2007 when engine manufacturer Tognum went public, and Europe’s biggest since Spain’s Bankia raised €3.1bn in July of last year.
Listing the 23 per cent stake of its O2 Germany on the stock market is part of Telefonica’s efforts to cut its €58bn debt.
Telefonica, which declined to comment, closed the order books on the sale at 1pm yesterday.
In Germany, O2 is the smallest mobile operator with roughly 16 per cent of subscribers, trailing Deutsche Telekom, Vodafone and Dutch group KPN’s E-Plus.
Some analysts have criticised O2’s targeted valuation as high compared to peers.