LONDON: London’s FTSE 100 marked its worst day in a week on Thursday dragged down by pharmaceutical and energy stocks, while UK-based cybersecurity firm Avast jumped to the top of the index amid merger talks.

The blue-chip FTSE 100 index ended 1.1% lower, weighed by drugmakers which fell 2.9%, with AstraZeneca and GlaxoSmithKline among the worst performers.

Avast Plc jumped 18.1% and was the top gainer on the FTSE 100 after revealing it was in advanced talks over a merger with peer NortonLifeLock Inc.

The FTSE 100 has gained 8.5% so far this year helped by record low interest rates, but a rise in inflationary pressures coupled with risks arising from a jump in local coronavirus infections have slowed the rise of the blue-chip index, leading it to underperform its wider European peers.

Energy sector dropped 2.5%, with oil majors Royal Dutch Shell and BP down 2.4% and 2.9%, respectively.

The mid-cap FTSE 250 index fell 1.0% as fears over rising inflation and a jump in virus cases affected the more domestically focused stocks.

Among stocks, the world’s largest credit data company Experian was the top boost to the FTSE 100, up 2.8%, after it raised its annual outlook and posted a 31% jump in its first-quarter revenue.

Bank of England Governor Andrew Bailey said the central bank would assess inflation data for things that could be temporary before taking a call on raising rates, while a roaring jobs market in June also showed growing inflation pressures from rising wages.

“There are a couple of central banks including the Bank of England where the narrative has shifted with noises starting around ending the measures. They are slowly prepping the markets before dropping the support as inflation figures are out of control,” said Keith Temperton, equity sales trader at Forte Securities.