By Sara Sjolin, MarketWatch

LONDON (MarketWatch)--Oil firms knocked the U.K.'s FTSE 100 index lower on Friday as oil prices slumped, offsetting relief that U.K. GDP numbers didn't miss expectations.

The benchmark slid 0.5% to close at 6,388.73, breaking a three-day winning streak. On the week, it climbed 1.2%.

Energy firms weighed the most on the index, as oil futures dropped more than 1%. Shares of BP PLC (BP) gave up 1.4%, BG Group PLC lost 1.3% and Royal Dutch Shell PLC (RDSB) fell 0.5%.

Pearson PLC dropped 2.6% after the publisher said its chief financial officer, Robin Freestone, is stepping down before the end of next year.

Tesco PLC dropped for a third straight day, down 1.3%. Shares of the supermarket chain sank 6.6% on Thursday, after it said its accounting error was bigger than initially estimated and revealed Chairman Richard Broadbent is stepping down.

Travel shares and airlines were also on the decline, after reports that a doctor who traveled back to New York from an Ebola-stricken region of Africa tested positive for the virus on Thursday. InterContinental Hotels Group PLC lost 1.9%, TUI Travel PLC fell 0.9% and easyJet PLC dropped 0.9%.

On the data front, the first estimate of third-quarter U.K. gross domestic product came in as expected, showing the economy expanded by 0.7%. Although the growth rate was a slowdown from the 0.9% in the second quarter, it still marked a seventh straight period of growth. The pound (GBPUSD) climbed after the data, trading at $1.6094 at the time of the European market close, up from $1.6031 ahead of the data.

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