Euro zone sentiment improved for the second consecutive month in October with investors' expectations boosted by monetary easing from central banks and by the top German court's approval for a new permanent bailout fund for the European currency bloc.

Sentix research group said on Monday its index tracking investor sentiment in the euro zone strengthened to -22.2 from September's -23.2, though it fell short of expectations in a Reuters poll that sentiment would rise to -20.8.

A sub-index of current euro zone sentiment rose modestly to -34.5 from -34.8 while the expectations component strengthened for the third straight month to -9.0 from -10.8, "which generally signals a change in trend", Sentix said in a statement.

"There were plenty of reasons for this: the constitutional court in Germany gave the ESM (European Stability Mechanism) the green light, the U.S. Federal Reserve began a third quantitative easing programme and the Bank of Japan also announced additional bond buying," Sentix said.

A separate index for Germany showed sentiment rising to 6.4 in October from 4.4 last month, underpinned by private investors' increased optimism in belated response to the European Central Bank's bond-buying plan announced last month.

German institutional investors trimmed their expectations slightly after strong surges in the two previous months, Sentix said.

An index for investor sentiment in the United States dipped to -1.5 from -1.3, one for Asia excluding Japan rose to 13.2 from 12.1 and an index for Japan improved to -13.5 from -14.9.

(Reporting by Stephen Brown)