GLOBAL MARKETS-Shares slide ahead of U.S. GDP as earnings disappoint

* European shares open down 0.4 percent on earnings worries

* Oil prices slip ahead of U.S. GDP report

* Dollar slips against yen as BOJ move awaited

LONDON, Oct 26 (Reuters) - European shares opened lower following a weak session in Asia as lacklustre earnings from tech giant Apple undermined confidence ahead of American growth data due later on Friday.

Apple, the most valuable public company in the United States, along with internet giant Amazon which posted a loss, joined a growing list of companies whose earnings reports have underlined the weak state of global demand.

``Disappointing figures from Apple and Amazon have struck a cautious note with investors, with both companies struggling with costs and lower margins,'' Markus Huber, a senior trader at ETX Capital said.

The FTSE Eurofirst 300 index of top European shares was down 0.4 percent in early deals with London's FTSE 100 , Paris's CAC-40 and Frankfurt's DAX all around 0.2 to 0.4 percent lower.

So far, 40 percent of European companies have missed third-quarter profit expectations, compared to around 30 percent in the United States, according to Thomson Reuters StarMine data.

The weaker tone in European markets was partly offset by data showing German consumer morale had hit its highest level in over five years going into November, suggesting domestic demand was holding up in Europe largest economy.

But most attention was fixed on U.S. third quarter GDP data due at 1230 GMT which is expected to show the world's biggest economy expanding at a sluggish annual rate of 1.9 percent, according to a Reuters survey of economists.

Ahead of the GDP data Brent crude LCOc1 slipped as low as $107.40 a barrel extending its losses to more than 3 percent this month as investors turn reluctant to build up positions ahead of U.S. elections in November.

The euro was down 0.1 percent at $1.2923 after problems emerged in negotiations with the Greek government over a new 13.5 billion euro package of austerity measures required to secure fresh aid.

The dollar was down about 0.4 percent at 79.99 yen but was still headed for a second week of gains, as markets geared up for the Bank of Japan to ease policy next week.

Japanese lawmakers have kept steady pressure on the BOJ to act by unveiling a 422.6 billion yen ($5.3 billion) economic stimulus package on Friday.