British Airways, the UK airline, was the most shorted of the FTSE 100 index last year, according to market monitor Data Explorers.

Between January and December 21, it had as much as 30% of its stock out on loan. The airline was hit by a combination of fears over the Icelandic ash cloud, strikes over pay and conditions, questions over its now-completed merger with Spanish rival Iberia, and its multi-billion pound pension deficit.