* FTSEurofirst 300 closes down 0.6 pct; volumes thin
* Biggest weekly loss since July as Santa rally peters out
* Autos the biggest gainer in 2010; banks the top loser (Updates to close)
By Simon Jessop
LONDON, Dec 31 (Reuters) - European shares ended the last trading day of 2010 lower in thin holiday trade, posting the biggest weekly fall since July as the December rally petered out, although they were still up 7.3 percent on the year.
The pan-European FTSEurofirst 300 <.FTEU3> index of top shares ended down 0.6 percent at 1,121.67 on Friday, although the monthly gain of over 5.1 percent remains the strongest since March.
With the majority of major markets already on holiday, including Germany, Spain and Italy, and others such as the UK and France working a shorter day, Friday volumes were low, at just 27 percent of the index's 30-day trading average.
In spite of the weak end to the year, most analysts expect further gains in 2011, fuelled by corporate balance sheet strength and government stimulus.
That balance sheet strength, as seen through improving profitability and stronger margins, meant equities remain cheap and this should provide confidence going into the new year, said Howard Wheeldon, strategist at BGC Capital Partners.
"Even after the rises we've had this year, equities are not overvalued," said Wheeldon, adding that with political and sovereign debt concerns continuing to spook some investors, equities offered "an interesting safe haven."
The scale of the market's bounce back from lows earlier in the year, on the back of the euro zone sovereign debt crisis, also gave cause for optimism heading into 2011, said Joshua Raymond, market strategist at City Index.
"We have rallied around 25 percent since the start of July which is a significant confidence booster."
Auto-sector stocks provided the biggest percentage rise over 2010, with the STOXX Europe 600 Automobiles & Parts <.SXAP> index up 45 percent on the year, followed by the STOXX Europe 600 Industrial Goods & Services <.SXNP> index, up 34 percent.
Banks proved the year's biggest laggard, beset by capital adequacy concerns and exposure to the sovereign debt crisis, and the STOXX Europe 600 Banks index <.SX7P> ended the year down 11 percent.
Among the biggest individual stock movers on Friday was
mining heavyweight BHP Billiton
Across Europe, Britain's FTSE 100 <.FTSE> and France's CAC 40 <.FCHI> both ended down 1.2 percent. (Additional reporting by Harpreet Bhal; Editing by James Dalgleish)