European stocks ended mixed on the last trading day of the year.

The pan-European Stoxx 600 index closed a shortened trading session 0.1% lower on Wednesday, with most sector indexes in negative territory.

The U.K.'s FTSE 100 ended the day down 0.2%, bringing the index to an annual gain of 21.5% – its strongest yearly gain since 2009.

Meanwhile, France's CAC 40 ended New Year's Eve down 0.2%, while Germany's DAX rose 0.6%. Italy's FTSE MIB gained 1.1%, bringing annual gains to 31.5% and its best year since 1998.

Markets were open for a half-day of trading on Wednesday, and will be closed on Thursday for the New Year's Day holiday before reopening on Friday.

Defense stocks rose for a second day, with Saab, Renk and Rheinmetall closing between 2% and 3% higher, bringing annual gains for shares to between 130% and 193%.

Biotech firm Abivax closed as the blue-chip index's top performer, up 3.8%, as well as the best performer over the year, boasting a 1,616% gain. The French company surprised investors with a better-than-expected clinical trial readout for its lead asset – a medicine for ulcerative colitis – over the summer, and has been the subject of speculation of an imminent buyout.

Regional stocks had extended gains to notch a fresh record high on Tuesday, with the pan-European Stoxx 600 index closing 0.7% higher.

London-listed Fresnillo was among the worst-performing stocks in the Stoxx 600 index on Wednesday, falling 2.3% after a 6% jump on Tuesday. Other mining stocks were also top performers in the previous trading session, with Anglo American, Antofagasta, and Glencore rising around 3% each, but were spared any big pullbacks on Wednesday.

Source : CNBC.com