By Carla Mozee, MarketWatch

LONDON (MarketWatch) -- U.K. stocks marked a third consecutive day of declines on Wednesday, moving in line with markets worldwide that keyed off Wall Street's slide in the previous session.

The FTSE 100 index fell 0.8% to 6,733.62, falling alongside the broader European market as tracked by the Stoxx Europe 600 . That index fell 1.1%, the sharpest drop since mid-April, according to FactSet data.

Benchmarks across Asia also closed lower overnight "as traders take cash off the table amid growing unease with the violence in Iraq," said ETX Capital on Wednesday, noting reports on Tuesday that at least 50 people were killed after Syrian warplanes hit targets in western Iraq.

"This rattled sentiment across global markets overnight, driving up oil prices," ETX Capital added. Prices for West Texas Intermediate crude (CLQ4) extended gains on Wednesday, trading above $106 a barrel, while Brent crude futures took a breather below $114 a barrel.

Oil shares in London climbed on Tuesday, but pulled back with Brent crude on Wednesday. BP PLC (BP) lost 1.3%, Royal Dutch Shell declined 1.1% and BG Group PLC moved 0.3% lower.

But Shire PLC (SHPGY) topped the FTSE 100 with a 2.6% advance after U.S. rival AbbVie Inc. (ABBV) said its proposed bid for Shire has a "compelling strategic rationale," and offers significant value to shareholders of both companies. Shire rejected a $46 billion offer from AbbVie last week, saying it undervalued the company.

More must-reads from MarketWatch:

British payday lender slapped with fine in fake law-firm scheme

Draghi's monetary blitz has failed to lift euro zone

Has the beginning of the end of the bull market begun?

Subscribe to WSJ: http://online.wsj.com?mod=djnwires