The FTSE 100 Index closed 3.7 points lower at 5662.4 today, with troubled security firm G4S comfortably the biggest faller.
Its shares fell 24.1p to 254.6p amid mounting pressure since its admission that the Olympics debacle will cost it as much as £50million this year.
National Grid was 10.5p lower at 682.5p after regulator Ofgem said it planned to allow £22billion of investment in the UK’s gas and high voltage electricity networks.
The company had hoped that bill increases could average between £15 and £20 by 2021 but Ofgem has limited this under its “price control” regulation.
National Grid is concerned that Ofgem’s proposals mean it will not be able to encourage the investment needed in the UK’s infrastructure and cover the implicit risk associated with such major projects.
Other high-profile fallers included Barclays on the day the industry’s Libor-rigging scandal returned to the spotlight, with MPs quizzing former chief operating officer Jerry del Missier.
Barclays’ shares were 4.45p lower at 157.7p, while Lloyds Banking Group was down 0.3p at 30p and Royal Bank of Scotland slipped 1.9p to 204.5p.
Software firm Sage fell 3%, or 9p to £2.76 after it said conditions in continental Europe remained tough, offsetting “good growth” in the UK and Ireland and improved trading in North America.
Technology firm Smiths Group was one of the biggest risers in the top flight, up 15p to £10.5 after it sold its stake in Cross Match Technologies for up to £49.4million. It also benefited from a broker upgrade.
David Barclay, of investment manager and financial planning specialist Brewin Dolphin in Aberdeen, noted FirstGroup 5.43% higher at 200.1p, Hunting adding 2.17% at £7.31 and SSE gaining 1.56% to £14.30 as well as Melrose Resources shedding 2.6% to 115.375p.