Airline gives profits forecast warning.
The German airline, which carried 104 million passengers across a fleet of 622 planes last year, said capacity growth from Middle Eastern carriers such as Emirates or Etihad on its US and European routes was putting pressure on fares amid the increased competition.
The business said it was lowering its operating profit forecast by as much as a third to [euro]1bn (PS806m) for this year and by 24% to [euro]2bn euros (PS1.6bn) in 2015.
The German airline's profits downgrade knocked UK-listed airlines, putting them among the biggest fallers on the FTSE 100. EasyJet fell more than 3% and International Airlines Group, which owns British Airways and Iberia, slipped almost 5%.
Lufthansa first warned in May that it was facing a series of price pressures that included a pilot's strike and currency fluctuations.
Lufthansa chief officer for finances and aviation services Simone Menne said: "The revenue risks mentioned when we presented the quarterly figures in early May have unfortunately materialised."
The airline added it would cut its capacity during the winter.