* FTSEurofirst 300 down 1.7 pct, posts weekly loss
* Santander slides after capital increase, dividend cut
* Euro zone banks fall as ECB stimulus optimism cools
By Francesco Canepa and Lionel Laurent
LONDON, Jan 9 (Reuters) - European shares posted a loss in the first full trading week of 2015, weighed down by a slide in banks, led by Spain's Santander after its capital increase, and oil companies.
Relief after stronger-than-expected U.S. jobs data proved short-lived and the pan-European FTSEurofirst 300 index dipped back late on Friday to close 1.7 percent lower at 1,345.60 points.
It was down 1.1 percent for the week despite a 2.9 percent bounce on Thursday.
"The bid from new money to start the year feels like it's faded," a trader said.
Euro zone banks, down 5.1 percent, weighed as expectations about a wide bond-buying programme from the European Central Bank cooled and heavyweight Santander slid over 13 percent after announcing a capital increase and dividend cut.
Traders said the discounted price of Santander's capital increase had hurt the stock, though some analysts said the move would pay off.
"This was a needed capital rebuild that addresses a known issue," Goldman Sachs analysts wrote in a note to clients.
The broader sector was under pressure as sources close to the discussions told Reuters that an ECB bond-buying programme may see national central banks buy some of the bonds, and set a ballpark figure for the overall size of the programme at 500 billion euros ($590 billion).
Energy stocks, down 2 percent, also dragged the market down as oil prices headed for a seventh straight weekly loss, slipping back towards $50 a barrel on Friday. Key producers are showing no sign of cutting output in the face of a supply glut.
The market had briefly cut its losses earlier after data showed U.S. job growth increased briskly in December, further strengthening the economy's fundamentals.
"If you're at all nervous about the U.S. economy, in terms of its effect on trading partners in Germany and the like, the answer is unquestionably at this point that it is doing just fine," said Dan Greenhaus, chief strategist at BTIG.
European bourses in 2014: link.reuters.com/pap87v
Asset performance in 2014: link.reuters.com/gap87v
Today's European research round-up
$1 = 0.8485 euros Reporting by Francesco Canepa; Editing by Dominic Evans