Oct. 6 (Bloomberg) -- BP Plc, Europe's second-largest oil company, slumped the most in more than six years in London trading as crude prices extended declines. Royal Dutch Shell Plc, the continent's biggest producer, fell the most since combining its Dutch and U.K. parent companies.

BP slid 38 pence, or 8.2 percent, to 429.75 pence, the steepest one-day decline since June 1992. Shell's Class-A shares in London lost 7.7 percent to 1,502 pence, the most since July 2005.

Oil fell for a fourth day in New York as the credit crisis deepened, adding to concerns that global economic growth will slow and reduce demand for fuels. Crude for November delivery retreated as much as $4.99 to $88.89 a barrel in New York. Futures are down 38 percent from a record $147.27 on July 11.

If oil prices slipped below $80 a barrel next year, BP would retain its ``hold'' rating while Shell would be cut to ``hold'' from ``buy,'' Jason Kenney, an Edinburgh-based analyst at ING Wholesale Banking, said in a note today. ``Given the uncertainty for sustainability of earnings and the likely profitability squeeze, we would see little to be optimistic about for the oil sector as a whole in such a scenario.''

Total

Total SA, Europe's third-largest oil company, had the largest one-day drop in almost 10 years, sliding 3.80 euros, or 8.9 percent, to 38.85 euros in Paris.

The oil and gas industry subgroup on the Dow Jones Europe Stoxx 600 slid 8.7 percent, the biggest decline since October 1987. The subgroup is down 33 percent this year.

Repsol YPF, the largest energy company in Spain, fell 7.2 percent to 19.22 euros in Madrid.

Eni SpA, Italy's largest oil company, slumped the most in Milan since the shares were first sold to the public in 1995. The stock fell 10 percent to 16.62 euros after ING, JPMorgan Chase & Co. and UBS AG cut their price targets for the company.

Shell has lost 29 percent this year, while BP has tumbled 30 percent. Total is down 32 percent. BP reports third-quarter earnings Oct. 28, followed by Shell on Oct. 30.

In terms of market value, Shell has been bypassed by Johnson & Johnson and JPMorgan Chase & Co., according to Bloomberg data. Exxon Mobil Corp. is the world's largest company in market value.

To contact the reporter on this story: Fred Pals in Amsterdam at fpals@bloomberg.net

Last Updated: October 6, 2008 12:08 EDT