LONDONSINGAPORE, Dec 21 Reuters Global shares edged up on Wednesday after the Bank of Japan rocked the markets by unexpectedly deciding to loosen its tight leash on government bond yields, with the yen then scoring its biggest oneday gain against the dollar in 24 years.

The MSCI AllWorld index rose 0.1 on the day, although it is on track for a 4.4 decline in December. This year, the index is set to have fallen for eight out of 12 months, on a par only with 2008 for the number of monthly losses in a calendar year on record.

In Europe, shares pared some of the previous day39;s declines, thanks in large part to a rally in sportswear stocks, after Nike, the world39;s largest sportswear company, beat quarterly revenue estimates. U.S. index futures , rose between 0.50.6, suggesting some of this strength may carry through to the Wall Street open later.

On Tuesday, the Bank of Japan BOJ widened its trading band for 10year government bond yields from 25 basis points bps either side of zero to 50 bps.

That triggered a leap in the yen, which had spent most of the year sliding because of Japan39;s low yields, as well as selling in Japan39;s stock market and a selloff for bonds around the world.

The decision by the BOJ, the last dovish bastion in the central bank world, has added to concern among investors about how the impact of rising interest rates and persistent inflation will affect the global economy.

Fund managers are adopting an extremely cautious approach to the start…