Europe's STOXX 600 closed at a record high on Wednesday, with healthcare stocks leading the way after a U.S.-Pfizer deal reduced uncertainty in the sector, while investors digested the beginning of a U.S. government shutdown.

The pan-European STOXX 600 surged 1.2% to log its biggest one-day percentage gain since July 23. Most regional bourses were also trading higher, with London's FTSE 100 at a record high.

Healthcare stocks jumped 5.4%, marking their biggest one-day performance since November 2008. On Tuesday, Pfizer agreed to lower prescription drug prices in the U.S. Medicaid programme in exchange for tariff relief.

"The sector generally has struggled over the last year or so and what we are hopefully beginning to see is some measure of clarity about what the rules of the game may look like," said Richard Flax, chief investment officer at Moneyfarm.

Other pharma stocks such as Ambu rose 9.3%, Sartorius 9.5%, Merck 10%, Roche 8.6% and AstraZeneca 11.2%.

Novartis gained 3.9% after the U.S. Food and Drug Administration approved its oral treatment for a type of chronic inflammatory skin disease.

All sectors were trading in the positive territory, but travel and leisure stocks bucked the trend with a 0.4% dip.

Source: Investing.com