The hangover from Pfizer's apparent failure to land rival AstraZeneca was also a factor in the lacklustre performance by the FTSE 100 Index, which dipped 42.5 points to 6802.
The top flight has fallen in both sessions this week as disappointing corporate results add to ongoing concerns over whether China can meet expectations for GDP growth of 7.5% this year.
The pound strengthened slightly against the US dollar, at 1.68, and the euro, at 1.22, as official figures showed that inflation rose for the first time in 10 months in April, putting pressure on the Bank of England over interest rates. Vodafone was the biggest faller in the top flight after it reported a drop in annual earnings to £12.8 billion and forecast a figure of between £11.4 and £11.9 billion this year as it focuses on a two-year investment programme.
Shares were more than 5% or 11.9p lower to 205.3p as its revenues fell 1.9% to £43.6 billion in the year to March 31, with service revenues off 4.3%.
M&S shares were 5p lower at 446p after it posted a third year in a row of declining profits, which will result in management and staff at the chain receiving no bonus this year.
The 1% share decline for M&S came even though underlying profits of £623 million were slightly better than expected and chief executive Marc Bolland said general merchandise sales were showing "early signs of improvement".
Meanwhile, Astra shares steadied after yesterday's heavy loss triggered by its refusal to engage with Pfizer over the US firm's cash and shares offer valuing the company at £55 a share or £69.4 billion.
Schroders, which holds a 2% stake in Astra, said it was disappointed by the decision and urged management to continue talks. Astra shares were 0.3p lower at 4287.2p.
Outside the top flight, shares in home repair insurance business Homeserve were more than 7% higher as it sought to draw a line under the fall-out from a mis-selling scandal dating between 2005 and 2011.
Full-year profits published yesterday were hit by a recent £30 million fine from the City regulator but chief executive Richard Harpin said the company had made good progress in stabilising the UK business, which has seen a smaller than expected reduction in customer numbers. Shares rose 23.2p to 340.3p.
The biggest risers on the FTSE 100 Index were Next up 90p at 6570, Carnival up 78p at 2380p, Whitbread up 51p at 3993p and Travis Perkins up 33p at 1649p.
The biggest fallers on the FTSE 100 Index were Randgold Resources down 60p at 6802p, Intertek down 58p at 4470p, SABMiller down 40p at 2926p and Royal Dutch Shell down 38.5p at 2553.5p.