Drug company AstraZeneca slipped to the bottom of the index after announcing a $381.5m (£244.9m) research and development expense in the fourth quarter of the year.
The company revealed that it would not be pushing forward with two drugs tackling ovarian cancer and major depressive disorder, respectively.
In a market statement, the company announced its core earnings per share would be at the lower end of forecasts.
The news saw AstraZeneca’s share price slide by 2.7% to 2,870p in early trading (at 0804 GMT).
Joining the company at the bottom was Eurasian Natural Resources and Prudential, both dropping 1.2% to 601p.
Medical devices manufacturer Smith & Nephew dropped 1.1% to 569.5p, while GlaxoSmithKline fell 1% to 1,435p.
Financial services group Old Mutual was the biggest climber (at 0804 GMT), rising 1% to 127p.
Recent entries to the FTSE 100 precious metals miner Polymetal and building supplies company CRH also rose, by 0.9% to 1,044p and 0.6% to 1,160p, respectively.
Engineer Meggitt was up 0.5% to 339p, while asset manager Ashmore increased by 0.3% to 319.6p.
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