Poor interim results from Vodafone have pushed the FTSE 100 down 0.9% to a two-month low in morning trading.
Vodafone shares fell 4.5% to 159p after its interim results missed expectations, prompting investors to sell the stock.
The income staple is struggling in the UK and Europe amid the slowdown in both regions, leading to a fall in Q2 organic service revenue growth after nine consecutive positive quarters.
That made the stock the largest faller in an index which was down 0.9% at 5,715 by mid-morning.
Share price falls for miners Anglo-American, Evraz and Kazakhmys added to that headline weakness, with Centrica also among the main strugglers, its shares down 2.7% at 311p.
The sole notable blue-chip riser was ITV, which leapt 8.8% to 94.5p after better-than-expected interim results.
Macro concerns also had a negative impact on equities across Europe, as worries over Greece's latest bailout tranche took hold again.
The euro fell 0.2% against the dollar, with Spanish 10-year bond yields rising to a six-week high of 5.93%. US futures pointed to a 0.5% fall in the S&P 500 at the open.
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