Rolls-Royce was one of the biggest FTSE 100 fallers today after it emerged it was involved in a corruption investigation relating to overseas intermediaries.
The aero-engines group spooked investors after it said it had passed information to the Serious Fraud Office on allegations of malpractice in Indonesia and China.
Shares closed 3% or 28.5p lower at 885p but the wider FTSE 100 Index rose 9.3 points to 5901.4 as mining stocks were buoyed by hopes over progress to resolve America's looming fiscal cliff.
Optimism over a deal, which would avert a series of automatic tax hikes and spending cuts, was high after President Barack Obama said late yesterday a deal was possible within a week.
Wall Street's Dow Jones Industrial Average saw a mixed start to trading, with further heavy losses from technology giant Apple after its biggest single-day loss in four years yesterday amid fears over competition in the smartphone market.
The pound was down against the US dollar at 1.60 amid higher hopes for avoiding the fiscal cliff on January 1, while sterling was up against the euro at 1.23.
In London, Eurasian Natural Resources moved 6.1p ahead to 283.3p and Antofagasta added 41p to 1337p.
Standard Chartered shares shrugged off confirmation that it expects to pay a total fine of 670 million US dollars (£416 million) to settle allegations that the bank breached sanctions with Iran.
It expects to pay another 330 million US dollars (£205 million) on top of the 340 million US dollars (£211 million) paid to New York's Department of Financial Services to settle the claims.
Standard warned the charge will push pre-tax profit growth down to a "mid-single digit rate" rather than the double-digit range, but shares still lifted 12p to 1500.5p on hopes the agreement will remove uncertainty.
Elsewhere in the top flight, accountancy software firm Sage was under pressure for a second straight session after results yesterday showed slowing growth in parts of Europe. Shares fell 2%, off 6.4p to 294p.
In the FTSE 250, Leeds-based electronic components firm Premier Farnell reported an 18% fall in underlying profits to £17.3 million in the third quarter.
But shares rose 3% or 5.6p to 182.7p as analysts said its performance would start turning around soon thanks to cost cutting efforts and easier comparatives.
Fellow FTSE 250 stock Dixons Retail was given a boost by a broker upgrade as Barclays said the demise of Comet would prove a game changer for the Currys and PC World parent company. Shares gained 1.1p to 27.6p.
Elsewhere, cinema chain Cineworld was in the spotlight after it announced a £47.3 million deal to buy art-house chain Picturehouse.
The acquisition will add another 21 cinemas and 60 screens to Cineworld's existing 80-strong chain. Shares rose 8.8p to 255p.
The biggest FTSE 100 risers were Antofagasta up 41p at 1337p, Eurasian Natural Resources ahead 6.1p at 283.3p, Vedanta Resources up 24p at 1118p and Johnson Matthey ahead 48p at 2411p.
The biggest FTSE 100 fallers were Weir Group down 64p at 1817p, Rolls-Royce off 28.5p at 885p, Pennon Group down 18p at 601p and Meggitt off 8.9p at 384p.